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.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://nvd.nist.gov/vuln/detail/CVE-2025-27556
• https://github.com/django/django/commit/2cb311f7b069723027fb5def4044d1816d7d2afd
• https://github.com/django/django/commit/39e2297210d9d2938c75fc911d45f0e863dc4821
• https://github.com/django/django/commit/8c6871b097b6c49d2a782c0d80d908bcbe2116f1
• https://github.com/django/django/commit/edc2716d01a6fdd84b173c02031695231bcee1f8
• https://docs.djangoproject.com/en/dev/releases/security
• https://github.com/django/django
• https://github.com/pypa/advisory-database/tree/main/vulns/django/PYSEC-2025-14.yaml
• https://groups.google.com/g/django-announce
• https://www.djangoproject.com/weblog/2025/apr/02/security-releases
• http://www.openwall.com/lists/oss-security/2025/04/02/2
• https://www.djangoproject.com/weblog/2025/apr/02/security-releases/
• https://docs.djangoproject.com/en/dev/releases/security/
• https://www.suse.com/security/cve/CVE-2025-27556.html
• https://security-tracker.debian.org/tracker/CVE-2025-27556