An issue was discovered in 5.1 before 5.1.14, 4.2 before 4.2.26, and 5.2 before 5.2.8. The methods `QuerySet.filter()`, `QuerySet.exclude()`, and `QuerySet.get()`, and the class `Q()`, are subject to SQL injection when using a suitably crafted dictionary, with dictionary expansion, as the `_connector` argument. Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank cyberstan for reporting this issue.

An issue was discovered in Django 4.2 before 4.2.24, 5.1 before 5.1.12, and 5.2 before 5.2.6. FilteredRelation is subject to SQL injection in column aliases, using a suitably crafted dictionary, with dictionary expansion, as the **kwargs passed QuerySet.annotate() or QuerySet.alias().

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().

An issue was discovered in Django 5.1 before 5.1.7, 5.0 before 5.0.13, and 4.2 before 4.2.20. The django.utils.text.wrap() method and wordwrap template filter are subject to a potential denial-of-service attack when used with very long strings.

An issue was discovered in Django 5.1 before 5.1.5, 5.0 before 5.0.11, and 4.2 before 4.2.18. Lack of upper-bound limit enforcement in strings passed when performing IPv6 validation could lead to a potential denial-of-service attack. The undocumented and private functions clean_ipv6_address and is_valid_ipv6_address are vulnerable, as is the django.forms.GenericIPAddressField form field. (The django.db.models.GenericIPAddressField model field is not affected.)

An issue was discovered in Django 5.1 before 5.1.4, 5.0 before 5.0.10, and 4.2 before 4.2.17. The strip_tags() method and striptags template filter are subject to a potential denial-of-service attack via certain inputs containing large sequences of nested incomplete HTML entities.

An issue was discovered in Django v5.1.1, v5.0.9, and v4.2.16. The django.contrib.auth.forms.PasswordResetForm class, when used in a view implementing password reset flows, allows remote attackers to enumerate user e-mail addresses by sending password reset requests and observing the outcome (only when e-mail sending is consistently failing).

An issue was discovered in Django 5.1 before 5.1.1, 5.0 before 5.0.9, and 4.2 before 4.2.16. The urlize() and urlizetrunc() template filters are subject to a potential denial-of-service attack via very large inputs with a specific sequence of characters.

An issue was discovered in Django 5.0 before 5.0.8 and 4.2 before 4.2.15. QuerySet.values() and values_list() methods on models with a JSONField are subject to SQL injection in column aliases via a crafted JSON object key as a passed *arg.

An issue was discovered in Django 5.0 before 5.0.8 and 4.2 before 4.2.15. The urlize and urlizetrunc template filters, and the AdminURLFieldWidget widget, are subject to a potential denial-of-service attack via certain inputs with a very large number of Unicode characters.

An issue was discovered in Django 5.0 before 5.0.8 and 4.2 before 4.2.15. The urlize() and urlizetrunc() template filters are subject to a potential denial-of-service attack via very large inputs with a specific sequence of characters.

An issue was discovered in Django 5.0 before 5.0.8 and 4.2 before 4.2.15. The floatformat template filter is subject to significant memory consumption when given a string representation of a number in scientific notation with a large exponent.

An issue was discovered in Django 5.0 before 5.0.7 and 4.2 before 4.2.14. get_supported_language_variant() was subject to a potential denial-of-service attack when used with very long strings containing specific characters.

An issue was discovered in Django 5.0 before 5.0.7 and 4.2 before 4.2.14. Derived classes of the django.core.files.storage.Storage base class, when they override generate_filename() without replicating the file-path validations from the parent class, potentially allow directory traversal via certain inputs during a save() call. (Built-in Storage sub-classes are unaffected.)

An issue was discovered in Django 5.0 before 5.0.7 and 4.2 before 4.2.14. The django.contrib.auth.backends.ModelBackend.authenticate() method allows remote attackers to enumerate users via a timing attack involving login requests for users with an unusable password.

An issue was discovered in Django 4.2 before 4.2.14 and 5.0 before 5.0.7. urlize and urlizetrunc were subject to a potential denial of service attack via certain inputs with a very large number of brackets.

In Django 3.2 before 3.2.25, 4.2 before 4.2.11, and 5.0 before 5.0.3, the django.utils.text.Truncator.words() method (with html=True) and the truncatewords_html template filter are subject to a potential regular expression denial-of-service attack via a crafted string. NOTE: this issue exists because of an incomplete fix for CVE-2019-14232 and CVE-2023-43665.

An issue was discovered in Django 3.2 before 3.2.24, 4.2 before 4.2.10, and Django 5.0 before 5.0.2. The intcomma template filter was subject to a potential denial-of-service attack when used with very long strings.

An issue was discovered in Django 3.2 before 3.2.23, 4.1 before 4.1.13, and 4.2 before 4.2.7. The NFKC normalization is slow on Windows. As a consequence, django.contrib.auth.forms.UsernameField is subject to a potential DoS (denial of service) attack via certain inputs with a very large number of Unicode characters.

In Django 3.2 before 3.2.22, 4.1 before 4.1.12, and 4.2 before 4.2.6, 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.

In Django 3.2 before 3.2.21, 4.1 before 4.1.11, and 4.2 before 4.2.5, django.utils.encoding.uri_to_iri() is subject to a potential DoS (denial of service) attack via certain inputs with a very large number of Unicode characters.

In Django 3.2 before 3.2.20, 4 before 4.1.10, and 4.2 before 4.2.3, EmailValidator and URLValidator are subject to a potential ReDoS (regular expression denial of service) attack via a very large number of domain name labels of emails and URLs.

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.

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.