CVE-2026-44899

Name	CVE-2026-44899
Description	Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the Image directive plugin validates the :width: and :height: options with a regex compiled as _num_re = re.compile(r"^\d+(?:\.\d*)?"). When the validated value is not a plain integer, render_block_image() inserts it directly into a style="width:...;" or style="height:...;" attribute. Because the value was accepted by the prefix-only regex, any CSS after the leading digits reaches the style= attribute verbatim and without escaping. This vulnerability is fixed in 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)
Debian Bugs	1138260

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)			1138260

Notes

[trixie] - mistune <no-dsa> (Minor issue)
[bookworm] - mistune <no-dsa> (Minor issue)
[bullseye] - mistune <no-dsa> (Minor issue)
https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9