CVE-2026-86430

Name	CVE-2026-86430
Description	league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing.
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
php-league-commonmark (PTS)	bookworm	2.3.9-1+deb12u1	vulnerable
	trixie	2.7.0-1+deb13u1	vulnerable
	forky, sid	2.10.0-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
php-league-commonmark	source	(unstable)	2.10.0-1

Notes

https://github.com/thephpleague/commonmark/security/advisories/GHSA-j8pm-gj4c-rq4x
Fixed by: https://github.com/thephpleague/commonmark/commit/d9375fadc308a63a02950a68d822417a6e4c33b2 (2.9.1)
Fixed by: https://github.com/thephpleague/commonmark/commit/0768217751fbfaeb8d76762f6944e9af7114295e (2.9.1)
Fixed by: https://github.com/thephpleague/commonmark/commit/e0036ef031fd36ec1c3c82db8743fc928b5271c8 (2.9.1)