CVE-2026-115353: Mistune before 3.3.0 Path Traversal via include Directive

Vulnerability summary

CVE-2026-115353 is a critical (CVSS 9.2) vulnerability in lepture mistune. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 32.9% of scored vulnerabilities.

Timeline

1. 22-10-2026
   PublishedVulnerability first disclosed.

Description

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

• 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.