CVE-2026-59925

Name	CVE-2026-59925
Description	Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inline_parser.py because the parser scans forward for matching close markers from every potential opening run, allowing denial of service in default Mistune parsing. This issue is fixed in version 3.3.0.
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	1141770

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
mistune (PTS)	bullseye	0.8.4-4	fixed
	bookworm	2.0.4-1	fixed
	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	Debian Bugs
mistune	source	bullseye	(not affected)
mistune	source	bookworm	(not affected)
mistune	source	(unstable)	(unfixed)	1141770

Notes

[trixie] - mistune <no-dsa> (Minor issue)
[bookworm] - mistune <not-affected> (Vulnerable parser construct introduced in 3.x rewrite)
[bullseye] - mistune <not-affected> (Vulnerable parser construct introduced in 3.x rewrite)
https://github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45
Fixed by: https://github.com/lepture/mistune/commit/5de41fb8e527004dbc363e047a3c380c9288c74f (v3.3.0)