A potential denial-of-service vulnerability has been identified in Django's urlize() and urlizetrunc() functions in django.utils.html. This vulnerability can be triggered by inputting huge strings containing a specific sequence of characters.

Affected versions of the Django package are vulnerable to Denial of Service (DoS) due to inefficient string concatenation when processing duplicate HTTP headers in ASGI mode. The ASGIRequest class combines repeated headers using repeated string concatenation, resulting in super-linear (quadratic) time complexity when processing requests with many duplicate headers.

An issue was discovered in Django 4.2 before 4.2.21, 5.1 before 5.1.9, and 5.2 before 5.2.1. The django.utils.html.strip_tags() function is vulnerable to a potential denial-of-service (slow performance) when processing inputs containing large sequences of incomplete HTML tags. The template filter striptags is also vulnerable, because it is built on top of strip_tags().

Django versions 2.2.25, 3.1.14 and 3.2.10 include a fix for CVE-2021-44420: In Django 2.2 before 2.2.25, 3.1 before 3.1.14, and 3.2 before 3.2.10, HTTP requests for URLs with trailing newlines could bypass upstream access control based on URL paths.
https://www.djangoproject.com/weblog/2021/dec/07/security-releases/

Django 2.2.26, 3.2.11 and 4.0.1 include a fix for CVE-2021-45452: Storage.save in Django 2.2 before 2.2.26, 3.2 before 3.2.11, and 4.0 before 4.0.1 allows directory traversal if crafted filenames are directly passed to it.
https://www.djangoproject.com/weblog/2022/jan/04/security-releases/

Affected versions of Django has a potential SQL injection vulnerability in the QuerySet.values() and QuerySet.values_list() methods. When used on models with a JSONField, these methods are susceptible to SQL injection through column aliases if a crafted JSON object key is passed as an argument.

Affected versions of Django are vulnerable to potential Denial of Service via certain inputs with a very large number of Unicode characters in django.utils.encoding.uri_to_iri().

Django 2.2.28, 3.2.13 and 4.0.4 include a fix for CVE-2022-28347: A SQL injection issue was discovered in QuerySet.explain() in Django 2.2 before 2.2.28, 3.2 before 3.2.13, and 4.0 before 4.0.4. This occurs by passing a crafted dictionary (with dictionary expansion) as the **options argument, and placing the injection payload in an option name.
https://www.djangoproject.com/weblog/2022/apr/11/security-releases

Django fixes a potential denial-of-service vulnerability in XML ``Deserializer``.

A security vulnerability has been discovered in certain versions of Django, affecting the password reset functionality. The PasswordResetForm class in django.contrib.auth.forms inadvertently allowed attackers to enumerate user email addresses by exploiting unhandled exceptions during the email sending process. This could be done by issuing password reset requests and observing the responses. Django has implemented a fix where these exceptions are now caught and logged using the django.contrib.auth logger, preventing potential information leakage through error responses.

Affected versions of the Django package are vulnerable to SQL Injection due to improper handling of column aliases containing periods in QuerySet.order_by() when combined with FilteredRelation. The QuerySet.order_by() method fails to properly sanitize column aliases that contain periods when the same alias is used in FilteredRelation via dictionary expansion. 
https://github.com/django/django/commit/90f5b10784ba5bf369caed87640e2b4394ea3314

Django 2.2.21, 3.1.9 and 3.2.1 include a fix for CVE-2021-31542: MultiPartParser, UploadedFile, and FieldFile allowed directory traversal via uploaded files with suitably crafted file names.
https://www.djangoproject.com/weblog/2021/may/04/security-releases

Affected versions of Django are vulnerable to potential denial-of-service in intcomma template filter when used with very long strings.

Django addresses a memory exhaustion issue in django.utils.numberformat.floatformat(). When floatformat receives a string representation of a number in scientific notation with a large exponent, it could lead to excessive memory consumption. To prevent this, decimals with more than 200 digits are now returned as-is.

In Django 3.2 before 3.2.16, 4.0 before 4.0.8, and 4.1 before 4.1.2, internationalized URLs were subject to a potential denial of service attack via the locale parameter, which is treated as a regular expression.

Affected versions of the `django` package are vulnerable to Download of Code Without Integrity Check due to improper handling of user-supplied input in the HTTP FileResponse class. The vulnerability arises because the Content-Disposition header of a FileResponse can be set using a filename derived from user input without sufficient validation. An attacker can exploit this by crafting a request that causes a file with malicious content to be downloaded, potentially executing arbitrary code on the client system when the file is opened.

Affected versions of the Django package are vulnerable to SQL Injection due to insufficient input sanitization in FilteredRelation column aliases. The FilteredRelation class fails to properly validate or escape column alias names when they are provided through dictionary expansion as keyword arguments to QuerySet.annotate() or QuerySet.alias() methods, allowing malicious SQL code to be injected directly into the generated database queries.

Django versions 2.2.19, 3.0.13 and 3.1.7 include a fix for CVE-2021-23336: Web cache poisoning via 'django.utils.http.limited_parse_qsl()'. Django contains a copy of 'urllib.parse.parse_qsl' which was added to backport some security fixes. A further security fix has been issued recently such that 'parse_qsl(' no longer allows using ';' as a query parameter separator by default.

Django 2.2.27, 3.2.12 and 4.0.2 include a fix for CVE-2022-23833: Denial-of-service possibility in file uploads.
https://www.djangoproject.com/weblog/2022/feb/01/security-releases

In Django 2.2 before 2.2.20, 3.0 before 3.0.14, and 3.1 before 3.1.8, MultiPartParser allowed directory traversal via uploaded files with suitably crafted file names. Built-in upload handlers were not affected by this vulnerability.

CVE-2025-64458: Affected versions of the Django package are vulnerable to Denial of Service (DoS) due to slow Unicode NFKC normalization on Windows being applied to untrusted inputs. The django.contrib.auth.views.LoginView and django.contrib.auth.views.LogoutView, and django.views.i18n.set_language normalize user-controlled strings using Python’s NFKC algorithm, which is unusually slow on Windows for huge Unicode sequences and can be triggered to consume excessive CPU.

Django 2.2.26, 3.2.11 and 4.0.1 include a fix for CVE-2021-45115: UserAttributeSimilarityValidator incurred significant overhead in evaluating a submitted password that was artificially large in relation to the comparison values. In a situation where access to user registration was unrestricted, this provided a potential vector for a denial-of-service attack.
https://www.djangoproject.com/weblog/2022/jan/04/security-releases/

Affected versions of Django are vulnerable to Denial-of-Service via django.utils.text.Truncator. The django.utils.text.Truncator chars() and words() methods (when used with html=True) are subject to a potential DoS (denial of service) attack via certain inputs with very long, potentially malformed HTML text. The chars() and words() methods are used to implement the truncatechars_html and truncatewords_html template filters, which are thus also vulnerable. NOTE: this issue exists because of an incomplete fix for CVE-2019-14232.

Django 4.1.7, 4.0.10 and 3.2.18 include a fix for CVE-2023-24580: Potential denial-of-service vulnerability in file uploads.
https://www.djangoproject.com/weblog/2023/feb/14/security-releases

Affected versions of Django are vulnerable to a potential denial-of-service (DoS) attack in the `django.utils.html.strip_tags()` method. The vulnerability occurs when the `strip_tags()` method or the `striptags` template filter processes inputs containing large sequences of nested, incomplete HTML entities.

Django affected versions are vulnerable to a potential SQL injection in the HasKey(lhs, rhs) lookup on Oracle databases. The vulnerability arises when untrusted data is directly used as the lhs value in the django.db.models.fields.json.HasKey lookup. However, applications using the jsonfield.has_key lookup with the __ syntax remain unaffected by this issue.

An issue was discovered in Django 5.2 before 5.2.3, 5.1 before 5.1.11, and 4.2 before 4.2.23. Internal HTTP response logging does not escape request.path, which allows remote attackers to potentially manipulate log output via crafted URLs. This may lead to log injection or forgery when logs are viewed in terminals or processed by external systems.

Affected versions of Django are vulnerable to a potential ReDoS (regular expression denial of service) in EmailValidator and URLValidator via a very large number of domain name labels of emails and URLs.

Django 2.2.26, 3.2.11 and 4.0.1 include a fix for CVE-2021-45116: An issue was discovered in Django 2.2 before 2.2.26, 3.2 before 3.2.11, and 4.0 before 4.0.1. Due to leveraging the Django Template Language's variable resolution logic, the dictsort template filter was potentially vulnerable to information disclosure, or an unintended method call, if passed a suitably crafted key.
https://www.djangoproject.com/weblog/2022/jan/04/security-releases

Django versions 3.2.2, 3.1.10 and 2.2.22 include a fix for CVE-2021-32052: In Django 2.2 before 2.2.22, 3.1 before 3.1.10, and 3.2 before 3.2.2 (with Python 3.9.5+), URLValidator does not prohibit newlines and tabs (unless the URLField form field is used). If an application uses values with newlines in an HTTP response, header injection can occur. Django itself is unaffected because HttpResponse prohibits newlines in HTTP headers.
https://www.djangoproject.com/weblog/2021/may/06/security-releases

Django 2.2.24, 3.1.12, and 3.2.4 include a fix for CVE-2021-33571: In Django 2.2 before 2.2.24, 3.x before 3.1.12, and 3.2 before 3.2.4, URLValidator, validate_ipv4_address, and validate_ipv46_address do not prohibit leading zero characters in octal literals. This may allow a bypass of access control that is based on IP addresses. (validate_ipv4_address and validate_ipv46_address are unaffected with Python 3.9.5+).
https://www.djangoproject.com/weblog/2021/jun/02/security-releases

Django 3.2.14 and 4.0.6 include a fix for CVE-2022-34265: Potential SQL injection via Trunc(kind) and Extract(lookup_name) arguments.
https://www.djangoproject.com/weblog/2022/jul/04/security-releases

Affected versions of Django are vulnerable to potential regular expression denial-of-service (REDoS). django.utils.text.Truncator.words() method (with html=True) and truncatewords_html template filter were subject to a potential regular expression denial-of-service attack using a suitably crafted string (follow up to CVE-2019-14232 and CVE-2023-43665).

Affected versions of the Django package are vulnerable to Path Traversal due to improper validation of file paths in the django.contrib.admindocs module. The `TemplateDetailView` view allows staff members to verify the existence of arbitrary files by manipulating the file path. An attacker with staff privileges can exploit this vulnerability to check for the presence of files outside the template root directories, and if the `admindocs` templates are customized to display file contents, they can also access the contents of these files.

Affected versions of Django are affected by a potential denial-of-service vulnerability in the django.utils.html.urlize() function. The urlize and urlizetrunc template filters were susceptible to a denial-of-service attack via certain inputs containing many brackets. An attacker could exploit this vulnerability to cause significant delays or crashes in the affected application.

The {% debug %} template tag in Django 2.2 before 2.2.27, 3.2 before 3.2.12, and 4.0 before 4.0.2 does not properly encode the current context. This may lead to XSS.

Affected versions of Django are affected by a username enumeration vulnerability caused by timing differences in the django.contrib.auth.backends.ModelBackend.authenticate() method. This method allowed remote attackers to enumerate users through a timing attack involving login requests for users with unusable passwords. The timing difference in the authentication process exposed whether a username was valid or not, potentially aiding attackers in gaining unauthorized access.

Django has a potential denial-of-service vulnerability in django.utils.html.urlize() and AdminURLFieldWidget. The urlize and urlizetrunc functions, along with AdminURLFieldWidget, are vulnerable to denial-of-service attacks when handling inputs with a very large number of Unicode characters.

Django 4.2.1, 4.1.9 and 3.2.19 include a fix for CVE-2023-31047: In Django 3.2 before 3.2.19, 4.x before 4.1.9, and 4.2 before 4.2.1, it was possible to bypass validation when using one form field to upload multiple files. This multiple upload has never been supported by forms.FileField or forms.ImageField (only the last uploaded file was validated). However, Django's "Uploading multiple files" documentation suggested otherwise.
https://www.djangoproject.com/weblog/2023/may/03/security-releases

Django 2.2.28, 3.2.13 and 4.0.4 include a fix for CVE-2022-28346: An issue was discovered in Django 2.2 before 2.2.28, 3.2 before 3.2.13, and 4.0 before 4.0.4. QuerySet.annotate(), aggregate(), and extra() methods are subject to SQL injection in column aliases via a crafted dictionary (with dictionary expansion) as the passed **kwargs.
https://www.djangoproject.com/weblog/2022/apr/11/security-releases

Django versions 3.1.13 and 3.2.5 include a fix for CVE-2021-35042: Django 3.1.x before 3.1.13 and 3.2.x before 3.2.5 allows QuerySet.order_by SQL injection if order_by is untrusted input from a client of a web application.
https://www.djangoproject.com/weblog/2021/jul/01/security-releases/
https://www.openwall.com/lists/oss-security/2021/07/02/2
https://docs.djangoproject.com/en/3.2/releases/security/
https://groups.google.com/forum/#%21forum/django-announce

Django 4.2.7, 4.1.13 and 3.2.23 include a fix for CVE-2023-46695: Potential denial of service vulnerability in UsernameField on Windows.
https://www.djangoproject.com/weblog/2023/nov/01/security-releases

Django 3.2.17, 4.0.9 and 4.1.6 includes a fix for CVE-2023-23969: In Django 3.2 before 3.2.17, 4.0 before 4.0.9, and 4.1 before 4.1.6, the parsed values of Accept-Language headers are cached in order to avoid repetitive parsing. This leads to a potential denial-of-service vector via excessive memory usage if the raw value of Accept-Language headers is very large.
https://www.djangoproject.com/weblog/2023/feb/01/security-releases

CVE-2025-64459: Affected versions of the Django package are vulnerable to SQL Injection due to improper input validation, allowing the internal _connector keyword argument to be accepted from untrusted dictionaries via expansion. The .filter(), .exclude(), and .get() methods on QuerySet, as well as the Q class, resolve **kwargs and will treat a supplied _connector value as the logical connector without constraining it to the expected set (AND/OR), permitting attacker-controlled tokens to influence SQL predicate construction.

Django fixes potential SQL injection in ``FilteredRelation`` column aliases on PostgreSQL.