CVE-2025-27556: django DoS — Fix

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.

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CVSS v3.1 Score

5.8

MEDIUM

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

Weakness Type (CWE)

CWE-770 CWE-770

Affected Products

Vendor	Product	Versions
djangoproject	django	5.0 — 5.0.14
djangoproject	django	5.1 — 5.1.8
microsoft	windows	All

References

Advisories & Patches

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/

Other References

http://www.openwall.com/lists/oss-security/2025/04/02/2

Frequently Asked Questions

What is CVE-2025-27556? +

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. It has a CVSS v3.1 base score of 5.8 (MEDIUM).

How severe is CVE-2025-27556? +

CVE-2025-27556 has a CVSS v3.1 score of 5.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-27556? +

CVE-2025-27556 affects products from djangoproject, microsoft, specifically: django, windows. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-27556? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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