CVE-2026-86435: Inefficient Algorithmic Complexity in thephpleague commonmark
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.
CVE-2026-86435: Inefficient Algorithmic Complexity in thephpleague commonmark
Description
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 v4.0
Score 8.7high
Affected software
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-07T12:34:31.457Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a9eb72eacd9273b49a9cff0
Added to database: 09/07/2026, 13:07:58 UTC
Last updated: 09/07/2026, 13:07:58 UTC
Views: 1
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