CVE-2026-115354: Mistune before 3.3.0 Arbitrary Local File Read via Include Directive

Vulnerability summary

CVE-2026-115354 is a high (CVSS 7.1) vulnerability in lepture mistune. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 40.6% of scored vulnerabilities.

Timeline

1. 22-10-2026
   PublishedVulnerability first disclosed.
2. 29-10-2026
   Last modifiedVulnerability information updated.

Description

Mistune before 3.3.0 contains a path traversal vulnerability in the opt-in Include directive that allows attackers to read local files by supplying relative or absolute include paths. Attackers who submit Markdown rendered via Markdown.read() can disclose files such as /etc/passwd and inject unescaped HTML or script content into rendered output.

• 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.