Pymdown Extensions

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.

Published: 2025-12-16T18:06:37.756Z
Updated: 2025-12-17T18:51:08.232Z

PyMdown Extensions is a set of extensions for the `Python-Markdown` markdown project. In affected versions an arbitrary file read is possible when using include file syntax. By using the syntax `--8<--"/etc/passwd"` or `--8<--"/proc/self/environ"` the content of these files will be rendered in the generated documentation. Additionally, a path relative to a specified, allowed base path can also be used to render the content of a file outside the specified base paths: `--8<-- "../../../../etc/passwd"`. Within the Snippets extension, there exists a `base_path` option but the implementation is vulnerable to Directory Traversal. The vulnerable section exists in `get_snippet_path(self, path)` lines 155 to 174 in snippets.py. Any readable file on the host where the plugin is executing may have its content exposed. This can impact any use of Snippets that exposes the use of Snippets to external users. It is never recommended to use Snippets to process user-facing, dynamic content. It is designed to process known content on the backend under the control of the host, but if someone were to accidentally enable it for user-facing content, undesired information could be exposed. This issue has been addressed in version 10.0. Users are advised to upgrade. Users unable to upgrade may restrict relative paths by filtering input.

Published: 2023-05-15T20:42:34.551Z
Updated: 2025-01-22T21:41:46.523Z