** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.

** DISPUTED ** Py throughout 1.11.0 allows remote attackers to conduct a ReDoS (Regular expression Denial of Service) attack via a Subversion repository with crafted info data because the InfoSvnCommand argument is mishandled.
https://github.com/pytest-dev/py/issues/287

Py 1.10.0 includes a fix for CVE-2020-29651: A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to redirect handling that drains connections by decompressing redirect response bodies without enforcing streaming read limits. The issue occurs when using urllib3’s streaming mode (for example, preload_content=False) while allowing redirects, because urllib3.response.HTTPResponse.drain_conn() would call HTTPResponse.read() in a way that decoded/decompressed the entire redirect response body even before any streaming reads were performed, effectively bypassing decompression-bomb safeguards.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to improper handling of highly compressed HTTP response bodies during streaming decompression. The urllib3.HTTPResponse methods stream(), read(), read1(), read_chunked(), and readinto() may fully decompress a minimal but highly compressed payload based on the Content-Encoding header into an internal buffer instead of limiting the decompressed output to the requested chunk size, causing excessive CPU usage and massive memory allocation on the client side.

Affected versions of the urllib3 package are vulnerable to Denial of Service (DoS) due to allowing an unbounded number of content-encoding decompression steps for HTTP responses. The HTTPResponse content decoding pipeline in urllib3 follows the Content-Encoding header and applies each advertised compression algorithm in sequence without enforcing a maximum chain length or effective output size, so a malicious peer can send a response with a very long encoding chain that triggers excessive CPU use and massive memory allocation during decompression.

Urllib3's ProxyManager ensures that the Proxy-Authorization header is correctly directed only to configured proxies. However, when HTTP requests bypass urllib3's proxy support, there's a risk of inadvertently setting the Proxy-Authorization header, which remains ineffective without a forwarding or tunneling proxy. Urllib3 does not recognize this header as carrying authentication data, failing to remove it during cross-origin redirects. While this scenario is uncommon and poses low risk to most users, urllib3 now proactively removes the Proxy-Authorization header during cross-origin redirects as a precautionary measure. Users are advised to utilize urllib3's proxy support or disable automatic redirects to handle the Proxy-Authorization header securely. Despite these precautions, urllib3 defaults to stripping the header to safeguard users who may inadvertently misconfigure requests.

Urllib3 1.26.17 and 2.0.5 include a fix for CVE-2023-43804: Urllib3 doesn't treat the 'Cookie' HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a 'Cookie' header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly.
https://github.com/urllib3/urllib3/security/advisories/GHSA-v845-jxx5-vc9f

Affected versions of urllib3 affected versions are vulnerable due to an issue where the authorization HTTP header is not removed when following a cross-origin redirect. This can result in credentials within the authorization header being exposed to unintended hosts or transmitted in cleartext. This vulnerability exists because of an incomplete fix for CVE-2018-20060, which addressed a similar issue case-sensitively.

Urllib3 1.24.3 includes a fix for CVE-2019-11236: CRLF injection is possible if the attacker controls the request parameter.
https://github.com/urllib3/urllib3/commit/5d523706c7b03f947dc50a7e783758a2bfff0532
https://github.com/urllib3/urllib3/issues/1553

Affected versions of urllib3 are vulnerable Improper Certificate Validation. Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to the use of the ssl_context, ca_certs, or ca_certs_dir argument.

Affected versions of urllib3 are vulnerable to an HTTP redirect handling vulnerability that fails to remove the HTTP request body when a POST changes to a GET via 301, 302, or 303 responses. This flaw can expose sensitive request data if the origin service is compromised and redirects to a malicious endpoint, though exploitability is low when no sensitive data is used. The vulnerability affects automatic redirect behavior. It is fixed in versions 1.26.18 and 2.0.7; update or disable redirects using redirects=False.
This vulnerability is specific to Python's urllib3 library.

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Urllib3 1.25.9 includes a fix for CVE-2020-26137: Urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.
https://github.com/python/cpython/issues/83784
https://github.com/urllib3/urllib3/pull/1800

Affected versions of this package are vulnerable to a TOCTOU (Time-of-Check to Time-of-Use) symlink vulnerability due to improper handling of symlinks during lock file creation. The vulnerability exists because the package does not adequately check for symlink manipulation between the time the lock file path is checked and the time it is used. An attacker can exploit this vulnerability by creating a malicious symlink, potentially leading to unauthorized access or modification of files, which could compromise the integrity and security of the system.

Affected versions of the filelock package are vulnerable to a Time-of-Check Time-of-Use (TOCTOU) Race Condition due to a race window between a write-permission check and lock file creation that does not prevent symlink substitution. The flaw is in filelock.SoftFileLock in src/filelock/_soft.py, where _acquire() calls raise_on_not_writable_file() and then performs os.open() on the lock path, allowing the filesystem state to change between the check and the use.

Affected versions of this package are vulnerable to Time-of-Check Time-of-Use (TOCTOU) Race Condition. The file locking mechanism in SoftFileLock._acquire() performs permission validation before file creation without using the O_NOFOLLOW flag, leading to a race window where attackers with local access can create symlinks that redirect lock operations to arbitrary files. An attacker can exploit this vulnerability by creating a malicious symlink during the brief window between permission check and file creation, causing the lock to operate on unintended target files and potentially enabling unauthorized access or file corruption.

Virtualenv version 20.21.0 addresses a race condition in `virtualenv.cli_run` where a `FileNotFoundError` could occur for a JSON file in `pypa/virtualenv/py_info/1`. This error happens if the underlying interpreter is updated, causing the JSON file to be deleted and rewritten.

Affected versions of the virtualenv package (up to and including 20.36.1) are vulnerable to Race Condition (TOCTOU) attacks due to non-atomic directory creation that is performed using check-then-act filesystem logic. The issue occurs in virtualenv’s directory creation operations for its app_data path and related lock file handling, where a directory existence check can be raced so a symlink is inserted before the subsequent creation or access step, redirecting operations to an unintended location.