In accordance with our security release policy, the Django team is issuing Django 4.0.1, Django 3.2.11, and Django 2.2.26. These release addresses the security issues detailed below. We encourage all users of Django to upgrade as soon as possible.
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.
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.