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.

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History

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

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cve-icon MITRE

Status: PUBLISHED

Assigner: DSF

Published:

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 : Received

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

Modified: 2026-03-03T16:16:20.970

Link: CVE-2026-25673

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses