CVE-2026-86433: Inefficient Algorithmic Complexity in thephpleague commonmark
commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection() performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks to cause parsing to take over 5 seconds, exhausting server resources.
CVE-2026-86433: 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 Attributes extension where AttributesListener::findTargetAndDirection() performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks to cause parsing to take over 5 seconds, exhausting 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: 6a9eb72eacd9273b49a9cfec
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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