CVE-2026-86435: high-severity vulnerability in thephpleague commonmark
commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote
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%
commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessive memory and CPU to exhaust server resources.
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-2026-86430HIGHleague/commonmark before 2.9.1 Denial of Service via parsingEPSS 0.5%CVE-2026-86428HIGHcommonmark 1.5.0 before 2.10.0 Denial of Service via AttributesEPSS 0.5%