Django 4.0.1 release notes

January 4, 2022

Django 4.0.1 fixes one security issue with severity “medium”, two security issues with severity “low”, and several bugs in 4.0.

CVE-2021-45115: Denial-of-service possibility in UserAttributeSimilarityValidator

UserAttributeSimilarityValidator incurred significant overhead evaluating submitted password that were artificially large in relative to the comparison values. On the assumption that access to user registration was unrestricted this provided a potential vector for a denial-of-service attack.

In order to mitigate this issue, relatively long values are now ignored by UserAttributeSimilarityValidator.

This issue has severity “medium” according to the Django security policy.

CVE-2021-45116: Potential information disclosure in dictsort template filter

Due to leveraging the Django Template Language’s variable resolution logic, the dictsort template filter was potentially vulnerable to information disclosure or unintended method calls, if passed a suitably crafted key.

In order to avoid this possibility, dictsort now works with a restricted resolution logic, that will not call methods, nor allow indexing on dictionaries.

As a reminder, all untrusted user input should be validated before use.

This issue has severity “low” according to the Django security policy.

CVE-2021-45452: Potential directory-traversal via Storage.save()

Storage.save() allowed directory-traversal if directly passed suitably crafted file names.

This issue has severity “low” according to the Django security policy.

Bugfixes

• Fixed a regression in Django 4.0 that caused a crash of assertFormsetError() on a formset named form (#33346).

• Fixed a bug in Django 4.0 that caused a crash on booleans with the RedisCache backend (#33361).

• Relaxed the check added in Django 4.0 to reallow use of a duck-typed HttpRequest in django.views.decorators.cache.cache_control() and never_cache() decorators (#33350).

• Fixed a regression in Django 4.0 that caused creating bogus migrations for models that reference swappable models such as auth.User (#33366).

• Fixed a long standing bug in Geometry Collections and Polygon that caused a crash on some platforms (reported on macOS based on the ARM64 architecture) (#32600).