What’s Vulnerable › Vulnerabilities

CVE-2025-27556

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-04-02 · updated 2026-06-17
• Weakness: CWE-770

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.

Affected products

• Django: from 5.0 before 5.0.14; from 5.1 before 5.1.8 — fixed in 5.0.14, 5.1.8

How to fix

Upgrade to a fixed version: Django 5.0.14, 5.1.8. Check the vendor advisory for mitigations.

References

• https://docs.djangoproject.com/en/dev/releases/security/
• 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

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