CVE-2026-59926

Name	CVE-2026-59926
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
mistune (PTS)	bullseye	0.8.4-4	vulnerable
	bookworm	2.0.4-1	vulnerable
	trixie	3.1.3-1	vulnerable
	forky, sid	3.1.4-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
mistune	source	(unstable)	(unfixed)

Notes

https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h
Fixed by: https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2 (v3.2.1)