An issue was discovered in Django 5.1 before 5.1.8 and 5.0 before 5.0.14. The NFKC normalization is slow on Windows. As a consequence, django.contrib.auth.views.LoginView, django.contrib.auth.views.LogoutView, and django.views.i18n.set_language are subject to a potential denial-of-service attack via certain inputs with a very large number of Unicode characters.