facelessuser pymdown-extensions up to 10.16.0 pymdownx.blocks.caption redos

Summaryinfo

A vulnerability has been found in facelessuser pymdown-extensions up to 10.16.0 and classified as problematic. This affects an unknown part of the component pymdownx.blocks.caption. The manipulation leads to redos. This vulnerability is traded as CVE-2025-68142. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in facelessuser pymdown-extensions up to 10.16.0. This issue affects an unknown part of the component pymdownx.blocks.caption. The manipulation with an unknown input leads to a redos vulnerability. Using CWE to declare the problem leads to CWE-1333. The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. Impacted is availability. The summary by CVE is:

PyMdown Extensions is a set of extensions for the `Python-Markdown` markdown project. Versions prior to 10.16.1 have a ReDOS bug found within the figure caption extension (`pymdownx.blocks.caption`). In systems that take unchecked user content, this could cause long hanges when processing the data if a malicious payload was crafted. This issue is patched in Release 10.16.1. As a workaround, those who process unknown user content without timeouts or other safeguards in place to prevent really large, malicious content being aimed at systems may avoid the use of `pymdownx.blocks.caption` until they're able to upgrade.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-68142 since 12/15/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1449.003 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 278975 (Linux Distros Unpatched Vulnerability : CVE-2025-68142), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 10.16.1 eliminates this vulnerability. Applying the patch b50d15a56850ed1408a284bba81cc019c6bd72e8 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 (278975). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• facelessuser

Name

• pymdown-extensions

Version

• 10.0
• 10.1
• 10.2
• 10.3
• 10.4
• 10.5
• 10.6
• 10.7
• 10.8
• 10.9
• 10.10
• 10.11
• 10.12
• 10.13
• 10.14
• 10.15
• 10.16.0

License

• open-source

Website

• Product: https://github.com/facelessuser/pymdown-extensions/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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