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.

An issue was discovered in the Multipart Request Parser in Django 3.2 before 3.2.18, 4.0 before 4.0.10, and 4.1 before 4.1.7. Passing certain inputs (e.g., an excessive number of parts) to multipart forms could result in too many open files or memory exhaustion, and provided a potential vector for a denial-of-service attack.

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.

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.

An issue was discovered in the HTTP FileResponse class in Django 3.2 before 3.2.15 and 4.0 before 4.0.7. An application is vulnerable to a reflected file download (RFD) attack that sets the Content-Disposition header of a FileResponse when the filename is derived from user-supplied input.

An issue was discovered in Django 3.2 before 3.2.14 and 4.0 before 4.0.6. The Trunc() and Extract() database functions are subject to SQL injection if untrusted data is used as a kind/lookup_name value. Applications that constrain the lookup name and kind choice to a known safe list are unaffected.