CVE-2026-86429

Name	CVE-2026-86429
Description	The league/commonmark (thephpleague/commonmark) library in versions >= 1.5.0 and < 2.9.1 contains quadratic parsing complexity in its SmartPunctExtension and AttributesExtension. When either extension is explicitly registered on the Environment (they are not enabled by default and are excluded from the standard CommonMark and GitHub-Flavored Markdown converters), an unauthenticated attacker can submit small, specially crafted Markdown documents — such as text alternating with unpaired quotes, contiguous runs of block-level attribute blocks, or repeated class attributes — to trigger disproportionate CPU consumption and cause a denial of service. Fixed in 2.9.1.
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
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-jjv6-8j6v-6j52
Fixed by: https://github.com/thephpleague/commonmark/commit/04a5d11ef6bf2d0b927310810d6a2a85d3c184b9 (2.9.1)
Fixed by: https://github.com/thephpleague/commonmark/commit/2f611b599c51661b005dc45c16ceaa547546e687 (2.9.1)