CVE-2025-27556

Summary

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.

Impact & exploitability

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Affected products we track (1)

Recommendation

Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.

Additional information

• NVD record
• https://docs.djangoproject.com/en/dev/releases/security/Advisory
• https://groups.google.com/g/django-announceAdvisory
• https://www.djangoproject.com/weblog/2025/apr/02/security-releases/Advisory
• http://www.openwall.com/lists/oss-security/2025/04/02/2Advisory