CVE-2026-86430: high-severity vulnerability in thephpleague commonmark
league/commonmark before 2.9.1 Denial of Service via parsing
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.5%
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Affected products
thephpleague · commonmarkRelated CVEs — thephpleague commonmark
In the same product, most dangerous first.
CVE-2026-71488HIGHleague/commonmark: Quadratic-time denial of service when parsing crafted MarkdownEPSS 0.6%CVE-2026-86429HIGHcommonmark before 2.9.1 Denial of Service via SmartPunct and AttributesEPSS 0.5%CVE-2026-86434HIGHcommonmark 2.0.0 through 2.8.3 Denial of Service via Slug CollisionEPSS 0.5%CVE-2026-86433HIGHcommonmark 1.5.0 before 2.8.4 Denial of Service via AttributesEPSS 0.5%CVE-2026-86428HIGHcommonmark 1.5.0 before 2.10.0 Denial of Service via AttributesEPSS 0.5%CVE-2024-58382HIGHleague/commonmark before 2.6.0 Denial of Service via Quadratic ComplexityEPSS 0.5%