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.
History

Thu, 05 Mar 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-770
References
Metrics threat_severity

None

threat_severity

Important


Wed, 04 Mar 2026 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Djangoproject
Djangoproject django
Vendors & Products Djangoproject
Djangoproject django

Tue, 03 Mar 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 03 Mar 2026 14:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Potential denial-of-service vulnerability in URLField via Unicode normalization on Windows
Weaknesses CWE-400
References

cve-icon MITRE

Status: PUBLISHED

Assigner: DSF

Published: 2026-03-03T14:28:28.601Z

Updated: 2026-03-03T15:26:02.764Z

Reserved: 2026-02-04T18:27:10.657Z

Link: CVE-2026-25673

cve-icon Vulnrichment

Updated: 2026-03-03T15:25:39.933Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-03-03T15:16:19.103

Modified: 2026-03-03T21:52:29.877

Link: CVE-2026-25673

cve-icon Redhat

Severity : Important

Publid Date: 2026-03-03T14:28:28Z

Links: CVE-2026-25673 - Bugzilla