CVE-2026-25673

CVE-2026-25673: Potential denial-of-service vulnerability in URLField via Unicode normalization on Windows

Vendor Djangoproject
Product Django
Weakness CWE-400
Published March 3, 2026
Last update June 30, 2026

CVSS base score

What the vulnerability does

01Description

An issue was discovered in 6.0 before 6.0.3, 5.2 before 5.2.12, and 4.2 before 4.2.29. `URLField.to_python()` in Django calls `urllib.parse.urlsplit()`, which performs NFKC normalization on Windows that is disproportionately slow for certain Unicode characters, allowing a remote attacker to cause denial of service via large URL inputs containing these characters. Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Seokchan Yoon for reporting this issue.

Key dates

02Disclosure timeline

March 3, 2026 CVE published
June 30, 2026 Record updated