CVE-2026-59924: Mistune: Arbitrary File Read via Include directive path traversal

Vulnerability summary

CVE-2026-59924 is a medium (CVSS 5.9) vulnerability in lepture mistune. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 40.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 08-07-2026
   PublishedVulnerability first disclosed.
2. 08-07-2026
   Last modifiedVulnerability information updated.

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Include.parse() joins and normalizes user-supplied include paths without verifying that the result remains within the intended markdown directory, allowing crafted include paths to access files outside that directory when markdown files are processed using md.read(). This issue is fixed in version 3.3.0.

• CWE-22Improper Limitation of a Pathname to a Restricted DirectoryThe product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.