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Vulnerability · Published Mar 3, 2026 · Assigned by DSF

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

High 7.5

In plain English

A high-severity uncontrolled resource consumption in Django from djangoproject. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 58% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.8%top 41.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.23py3-django4.2.29-r0ALPINE-CVE-2026-25673
PyPIdjango6.0.3GHSA-8p8v-wh79-9r56
PyPIdjango5.2.12GHSA-8p8v-wh79-9r56
PyPIdjango4.2.29GHSA-8p8v-wh79-9r56
PyPIdjango4.2.29, 5.2.12, 6.0.3PYSEC-2026-2448

Affected products (as reported)

VendorProductVersions
djangoproject Django 6.0 – before 6.0.35.2 – before 5.2.124.2 – before 4.2.29

Weakness: CWE-400, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References