py-pdf pypdf up to 6.9.x XMP Metadata xml entity expansion

Summaryinfo

A vulnerability, which was classified as problematic, was found in py-pdf pypdf up to 6.9.x. The affected element is an unknown function of the component XMP Metadata Handler. Such manipulation leads to xml entity expansion. This vulnerability is listed as CVE-2026-40260. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in py-pdf pypdf up to 6.9.x. Affected by this issue is some unknown functionality of the component XMP Metadata Handler. The manipulation with an unknown input leads to a xml entity expansion vulnerability. Using CWE to declare the problem leads to CWE-776. The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities. Impacted is availability. CVE summarizes:

pypdf is a free and open-source pure-python PDF library. In versions prior to 6.10.0, manipulated XMP metadata entity declarations can exhaust RAM. An attacker who exploits this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the XMP metadata. This issue has been fixed in version 6.10.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-40260 since 04/10/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 307345 (Linux Distros Unpatched Vulnerability : CVE-2026-40260), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.10.0 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch b15a374e5ca648d4878e57c3b2c0551e7f8cc7f8 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (307345). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• py-pdf

Name

• pypdf

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9

License

• open-source

Website

• Product: https://github.com/py-pdf/pypdf/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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