An issue was discovered in Pip (all versions) because it installs the version with the highest version number, even if the user had intended to obtain a private package from a private index. This only affects use of the --extra-index-url option, and exploitation requires that the package does not already exist in the public index (and thus the attacker can put the package there with an arbitrary version number). A warning was added about this behavior in version 21.1.
NOTE: it has been reported that this is intended functionality and the user is responsible for using --extra-index-url securely.

Pip 21.1 updates its dependency 'urllib3' to v1.26.4 due to security issues.

Versions of Pip prior to 19.2 are vulnerable to a directory traversal attack during the installation process from a URL. This vulnerability stems from improperly handling filenames in the Content-Disposition header that include path traversal sequences, potentially allowing unauthorized overwrite of critical files such as /root/.ssh/authorized_keys. The flaw is specifically found in the _download_http_url function within _internal/download.py.

Affected versions of the pip package are vulnerable to Path Traversal due to an incorrect directory containment check when extracting wheel archives. In src/pip/_internal/utils/unpacking.py, the is_within_directory() helper used os.path.commonprefix() (character-by-character) to compare directory and target paths, allowing crafted paths like a parent-directory substring match to be treated as safely inside the installation directory.

A flaw was found in python-pip in the way it handled Unicode separators in git references. A remote attacker could possibly use this issue to install a different revision on a repository. The highest threat from this vulnerability is to data integrity.

Affected versions of the pip package are vulnerable to Arbitrary File Overwrite due to improper validation of symbolic link targets in the fallback tar extraction code. In src/pip/_internal/utils/unpacking.py, the _untar_without_filter routine used when the Python tarfile module lacks PEP 706 (no tarfile.data_filter) extracted symlink members with tar._extract_member without verifying that link destinations resolve under the extraction root, a check later added via the is_symlink_target_in_tar helper.

Affected versions of Pip are vulnerable to Command Injection. When installing a package from a Mercurial VCS URL (ie "pip install hg+...") with pip prior to v23.3, the specified Mercurial revision could be used to inject arbitrary configuration options to the "hg clone" call (ie "--config"). Controlling the Mercurial configuration can modify how and which repository is installed. This vulnerability does not affect users who aren't installing from Mercurial.

Pip solves a security vulnerability that previously allowed maliciously crafted wheel files to execute unauthorized code during installation.

Lxml 4.2.5 includes a fix for CVE-2018-19787: lxml/html/clean.py in the lxml.html.clean module does not remove javascript: URLs that use escaping, allowing a remote attacker to conduct XSS attacks, as demonstrated by "j a v a s c r i p t:" in Internet Explorer. This is a similar issue to CVE-2014-3146.

Affected versions of the lxml package are vulnerable to XML External Entity Injection due to insecure default parser configuration that resolves external entities. The iterparse() function and the ETCompatXMLParser() class both default to resolve_entities=True, so untrusted XML input processed through either parser will expand external entity references and read referenced local files from the host. An attacker who supplies a crafted XML document to an application using these parsers in their default configuration can read sensitive local files and exfiltrate their contents through the parsed output.

Lxml 4.9.1 includes a fix for CVE-2022-2309: NULL Pointer Dereference allows attackers to cause a denial of service (or application crash). This only applies when lxml is used together with libxml2 2.9.10 through 2.9.14. libxml2 2.9.9 and earlier are not affected. It allows triggering crashes through forged input data, given a vulnerable code sequence in the application. The vulnerability is caused by the iterwalk function (also used by the canonicalize function). Such code shouldn't be in wide-spread use, given that parsing + iterwalk would usually be replaced with the more efficient iterparse function. However, an XML converter that serialises to C14N would also be vulnerable, for example, and there are legitimate use cases for this code sequence. If untrusted input is received (also remotely) and processed via iterwalk function, a crash can be triggered.

Lxml 4.6.2 includes a fix for CVE-2020-27783: A XSS vulnerability was discovered in python-lxml's clean module. The module's parser didn't properly imitate browsers, which caused different behaviors between the sanitizer and the user's page. A remote attacker could exploit this flaw to run arbitrary HTML/JS code.

In lxml before 4.4.0, when writing to file paths that contain the URL escape character '%', the file path could wrongly be mangled by URL unescaping and thus write to a different file or directory.  Code that writes to file paths that are provided by untrusted sources, but that must work with previous versions of lxml, should best either reject paths that contain '%' characters, or otherwise make sure that the path does not contain maliciously injected '%XX' URL hex escapes for paths like '../'.
https://github.com/lxml/lxml/commit/0245aba002f069a0b157282707bdf77418d1b5be

Lxml version 4.6.3 includes a fix for CVE-2021-28957: An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formation attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML.
https://bugs.launchpad.net/lxml/+bug/1888153

Lxml 4.6.5 includes a fix for CVE-2021-43818: Prior to version 4.6.5, the HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should upgrade to lxml 4.6.5 to receive a patch.

Twine 2.0.0 updates requests to 2.20 (or later) to include a security fix.

An issue was discovered in Pip (all versions) because it installs the version with the highest version number, even if the user had intended to obtain a private package from a private index. This only affects use of the --extra-index-url option, and exploitation requires that the package does not already exist in the public index (and thus the attacker can put the package there with an arbitrary version number). A warning was added about this behavior in version 21.1.
NOTE: it has been reported that this is intended functionality and the user is responsible for using --extra-index-url securely.

Pip 21.1 updates its dependency 'urllib3' to v1.26.4 due to security issues.

Versions of Pip prior to 19.2 are vulnerable to a directory traversal attack during the installation process from a URL. This vulnerability stems from improperly handling filenames in the Content-Disposition header that include path traversal sequences, potentially allowing unauthorized overwrite of critical files such as /root/.ssh/authorized_keys. The flaw is specifically found in the _download_http_url function within _internal/download.py.

Affected versions of the pip package are vulnerable to Path Traversal due to an incorrect directory containment check when extracting wheel archives. In src/pip/_internal/utils/unpacking.py, the is_within_directory() helper used os.path.commonprefix() (character-by-character) to compare directory and target paths, allowing crafted paths like a parent-directory substring match to be treated as safely inside the installation directory.

A flaw was found in python-pip in the way it handled Unicode separators in git references. A remote attacker could possibly use this issue to install a different revision on a repository. The highest threat from this vulnerability is to data integrity.

Affected versions of the pip package are vulnerable to Arbitrary File Overwrite due to improper validation of symbolic link targets in the fallback tar extraction code. In src/pip/_internal/utils/unpacking.py, the _untar_without_filter routine used when the Python tarfile module lacks PEP 706 (no tarfile.data_filter) extracted symlink members with tar._extract_member without verifying that link destinations resolve under the extraction root, a check later added via the is_symlink_target_in_tar helper.

Affected versions of Pip are vulnerable to Command Injection. When installing a package from a Mercurial VCS URL (ie "pip install hg+...") with pip prior to v23.3, the specified Mercurial revision could be used to inject arbitrary configuration options to the "hg clone" call (ie "--config"). Controlling the Mercurial configuration can modify how and which repository is installed. This vulnerability does not affect users who aren't installing from Mercurial.

Pip solves a security vulnerability that previously allowed maliciously crafted wheel files to execute unauthorized code during installation.

Lxml 4.2.5 includes a fix for CVE-2018-19787: lxml/html/clean.py in the lxml.html.clean module does not remove javascript: URLs that use escaping, allowing a remote attacker to conduct XSS attacks, as demonstrated by "j a v a s c r i p t:" in Internet Explorer. This is a similar issue to CVE-2014-3146.

Affected versions of the lxml package are vulnerable to XML External Entity Injection due to insecure default parser configuration that resolves external entities. The iterparse() function and the ETCompatXMLParser() class both default to resolve_entities=True, so untrusted XML input processed through either parser will expand external entity references and read referenced local files from the host. An attacker who supplies a crafted XML document to an application using these parsers in their default configuration can read sensitive local files and exfiltrate their contents through the parsed output.

Lxml 4.9.1 includes a fix for CVE-2022-2309: NULL Pointer Dereference allows attackers to cause a denial of service (or application crash). This only applies when lxml is used together with libxml2 2.9.10 through 2.9.14. libxml2 2.9.9 and earlier are not affected. It allows triggering crashes through forged input data, given a vulnerable code sequence in the application. The vulnerability is caused by the iterwalk function (also used by the canonicalize function). Such code shouldn't be in wide-spread use, given that parsing + iterwalk would usually be replaced with the more efficient iterparse function. However, an XML converter that serialises to C14N would also be vulnerable, for example, and there are legitimate use cases for this code sequence. If untrusted input is received (also remotely) and processed via iterwalk function, a crash can be triggered.

Lxml 4.6.2 includes a fix for CVE-2020-27783: A XSS vulnerability was discovered in python-lxml's clean module. The module's parser didn't properly imitate browsers, which caused different behaviors between the sanitizer and the user's page. A remote attacker could exploit this flaw to run arbitrary HTML/JS code.

In lxml before 4.4.0, when writing to file paths that contain the URL escape character '%', the file path could wrongly be mangled by URL unescaping and thus write to a different file or directory.  Code that writes to file paths that are provided by untrusted sources, but that must work with previous versions of lxml, should best either reject paths that contain '%' characters, or otherwise make sure that the path does not contain maliciously injected '%XX' URL hex escapes for paths like '../'.
https://github.com/lxml/lxml/commit/0245aba002f069a0b157282707bdf77418d1b5be

Lxml version 4.6.3 includes a fix for CVE-2021-28957: An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formation attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML.
https://bugs.launchpad.net/lxml/+bug/1888153

Lxml 4.6.5 includes a fix for CVE-2021-43818: Prior to version 4.6.5, the HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should upgrade to lxml 4.6.5 to receive a patch.

Twine 2.0.0 updates requests to 2.20 (or later) to include a security fix.