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.
https://www.djangoproject.com/weblog/2023/nov/01/security-releases/
https://security.netapp.com/advisory/ntap-20231214-0001/