GHSA-58cw-g322-p94v
Mistune has XSS via unescaped figclass/figwidth in Figure directive
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
In `src/mistune/directives/image.py`, the `render_figure()` function concatenates `figclass` and `figwidth` options directly into HTML attributes without escaping (lines 152-168).
This allows attribute injection and XSS even when `HTMLRenderer(escape=True)` is used, because these values bypass the inline renderer.
Other attributes in the same file (src, alt, style) are properly escaped; figclass/figwidth were missed.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/lepture/mistune/security/advisories/GHSA-58cw-g322-p94v
- https://nvd.nist.gov/vuln/detail/CVE-2026-44896
- https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2
- https://github.com/lepture/mistune
- https://github.com/pypa/advisory-database/tree/main/vulns/mistune/PYSEC-2026-168.yaml