Vulnerability Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mistune Project | Mistune | < 3.3.0 |
Related Weaknesses (CWE)
References
- https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbacPatch
- https://github.com/lepture/mistune/releases/tag/v3.2.1Release Notes
- https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72hVendor Advisory
FAQ
What is CVE-2026-59926?
CVE-2026-59926 is a vulnerability with a CVSS score of 6.1 (MEDIUM). Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into th...
How severe is CVE-2026-59926?
CVE-2026-59926 has been rated MEDIUM with a CVSS base score of 6.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59926?
Check the references section above for vendor advisories and patch information. Affected products include: Mistune Project Mistune.