CVE-2026-86433

HIGHCVSS 7.5

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.

Timeline

Published:September 7th, 2026 1:20 PM

Last modified:September 7th, 2026 1:20 PM

CVSS Scoring

CVSS v3: 7.5 (HIGH)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses (CWE)

CWE-407

References & Reports

Advisories, patches, and third-party reports

https://github.com/thephpleague/commonmark/security/advisories/GHSA-g2gp-3wwq-f4ph
https://www.vulncheck.com/advisories/commonmark-1.5.0-before-2.8.4-denial-of-service-via-attributes

Source: NIST NVD · Data may lag official sources by up to one minute