py-pdf pypdf up to 6.21.0 DCTDecode Filter input validation

Summaryinfo

A vulnerability labeled as critical has been found in py-pdf pypdf up to 6.21.0. This impacts an unknown function of the component DCTDecode Filter. Executing a manipulation can lead to input validation. This vulnerability is registered as CVE-2026-113786. It is possible to launch the attack remotely. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in py-pdf pypdf up to 6.21.0 and classified as critical. This vulnerability affects an unknown part of the component DCTDecode Filter. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.1, an attacker can craft a PDF containing image data labeled with the /DCTDecode filter that causes Pillow to select and invoke an unintended image parser when the image is loaded. Environments without the optional Pillow dependency are not affected. This issue is fixed in version 6.21.1.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-113786 since 10/20/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

Upgrading to version 6.21.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-107286). 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
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21.0

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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