Django up to 4.2.28/5.2.11/6.0.2 on Windows NFKC Normalization urllib.parse.urlsplit resource consumption

Summaryinfo

A vulnerability was found in Django up to 4.2.28/5.2.11/6.0.2 on Windows and classified as problematic. This affects the function urllib.parse.urlsplit of the component NFKC Normalization. Such manipulation leads to resource consumption. This vulnerability is listed as CVE-2026-25673. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Django up to 4.2.28/5.2.11/6.0.2 on Windows and classified as problematic. Affected by this issue is the function urllib.parse.urlsplit of the component NFKC Normalization. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at docs.djangoproject.com. This vulnerability is handled as CVE-2026-25673 since 02/04/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 300915 (Python Library Django 4.2.x < 4.2.29 / 5.2.x < 5.2.12 / 6.0.x < 6.0.3 DoS), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.2.29, 5.2.12 or 6.0.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (300915) and CERT Bund (WID-SEC-2026-1730). Once again VulDB remains the best source for vulnerability data.

Affected

• Xerox FreeFlow Print Server

Productinfo

Type

• Content Management System

Name

• Django

Version

• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5
• 4.2.6
• 4.2.7
• 4.2.8
• 4.2.9
• 4.2.10
• 4.2.11
• 4.2.12
• 4.2.13
• 4.2.14
• 4.2.15
• 4.2.16
• 4.2.17
• 4.2.18
• 4.2.19
• 4.2.20
• 4.2.21
• 4.2.22
• 4.2.23
• 4.2.24
• 4.2.25
• 4.2.26
• 4.2.27
• 4.2.28
• 5.2.0
• 5.2.1
• 5.2.2
• 5.2.3
• 5.2.4
• 5.2.5
• 5.2.6
• 5.2.7
• 5.2.8
• 5.2.9
• 5.2.10
• 5.2.11
• 6.0.0
• 6.0.1
• 6.0.2

License

• open-source

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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