GHSA-g97x-gvcm-x72h
Mistune: XSS via unescaped class option in Admonition directive
At a glance
- Published
- Updated
- CVE
- CVE-2026-59926
- Aliases
- PYSEC-2026-2214
- CVSS_V4
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
Description
In `src/mistune/directives/admonition.py`, the `render_admonition()` function concatenates the `:class:` option directly into the HTML class attribute without escaping (lines 63-68). This allows attribute injection and XSS even when `HTMLRenderer(escape=True)` is used. The directive name parameter is safe (validated against whitelist), but the class option comes from raw user input.
Affected packages
| Package | Versions |
|---|---|
| PyPI · mistune | introduced 0, fixed 3.3.0 |
References
- https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-59926 ADVISORY
- https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2 WEB
- https://github.com/lepture/mistune PACKAGE
- https://github.com/lepture/mistune/releases/tag/v3.2.1 WEB
- https://github.com/pypa/advisory-database/tree/main/vulns/mistune/PYSEC-2026-2214.yaml WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |