CVE-2026-86430

EUVD-2026-72388
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 41.38%
Affected Products (NVD)
VendorProductVersion
thephpleaguecommonmark
𝑥
< 2.9.1
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
php-league-commonmark
bookworm
vulnerable
forky
2.10.3-1
fixed
sid
2.10.4-1
fixed
trixie
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
php-league-commonmark
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
Common Weakness Enumeration
References
https://github.com/thephpleague/commonmark/security/advisories/GHSA-j8pm-gj4c-rq4x
https://www.vulncheck.com/advisories/league-commonmark-before-2.9.1-denial-of-service-via-parsing