CVE-2026-86428

Name	CVE-2026-86428
Description	commonmark versions from 1.5.0 before 2.10.0 contain a denial of service vulnerability in the AttributesExtension when processing distinctly-named attributes. Attackers can submit Markdown with numerous distinct attribute names to cause quadratic-time attribute merging and filtering, consuming disproportionate CPU resources and preventing 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-8rr7-cvq3-gmfh
Fixed by: https://github.com/thephpleague/commonmark/commit/f27eb720972490b5af4dbb635ad8634529faf9f2 (2.10.0)