CVE-2026-115355: Mistune: Path Traversal and XSS in Include directive
The Include directive in src/mistune/directives/include.py does not validate that the resolved file path stays within the source directory, allowing path traversal via ../ sequences to read arbitrary files.
Additionally, error messages and included file contents are rendered without HTML escaping, leading to XSS even when escape=True.
Affected functions:
- Path resolution (lines 27-31)
block_error()in html.py (line 140)render_html_include()(line 72)
The Include plugin must be explicitly enabled via the plugins parameter.
References
- github.com/advisories/GHSA-h7ww-273w-6cm8
- github.com/lepture/mistune/commit/1bef343ade163fc3bb95572b15be720084cdb993
- github.com/lepture/mistune/releases/tag/v3.3.0
- github.com/lepture/mistune/security/advisories/GHSA-h7ww-273w-6cm8
- nvd.nist.gov/vuln/detail/CVE-2026-115355
- www.vulncheck.com/advisories/mistune-before-3.3.0-path-traversal-and-xss-via-include-directive
Code Behaviors & Features
Detect and mitigate CVE-2026-115355 with GitLab Dependency Scanning
Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →