CVE-2025-27556

Name	CVE-2025-27556
Description	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.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-django (PTS)	bullseye	2:2.2.28-1~deb11u2	fixed
	bullseye (security)	2:2.2.28-1~deb11u6	fixed
	bookworm, bookworm (security)	3:3.2.19-1+deb12u1	fixed
	sid, trixie	3:4.2.20-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
python-django	source	(unstable)	(not affected)

- python-django <not-affected> (Windows-specific)
https://www.djangoproject.com/weblog/2025/apr/02/security-releases/