CVE-2026-25673

Potential denial-of-service vulnerability in URLField via Unicode normalization on Windows

State: Published
Severity: 7.5 High
Published: Mar 3, 2026
Updated: Jul 15, 2026
Reserved: Feb 4, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CISA-ADP
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	redhat-SADP

Weaknesses

CWE-400 Uncontrolled Resource Consumption
CWE-770 Allocation of Resources Without Limits or Throttling

Affected Products

Product	Versions
Djangodjangoproject	6.0 to before 6.0.3Affected 6.0.3Not affected 5.2 to before 5.2.12Affected 5.2.12Not affected 4.2 to before 4.2.29Affected 4.2.29Not affected

References

Django security archivevendor-advisory
Django releases announcementsmailing-list
Django security releases issued: 6.0.3, 5.2.12, and 4.2.29vendor-advisory
https://access.redhat.com/security/cve/CVE-2026-25673vdb-entry
RHBZ#2444115issue-tracking
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25673.json

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