CVE-2026-86433CWE-407

CVE-2026-86433

High · published September 7, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
42.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
8.7 · 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
EPSS
0.00509 · 42.6th percentile
Weakness
CWE-407 · Inefficient Algorithmic Complexity
Published
2026-09-07T17:20Z
References (2)
https://github.com/thephpleague/commonmark/security/advisories/GHSA-g2gp-3wwq-f4ph · [email protected]https://www.vulncheck.com/advisories/commonmark-1.5.0-before-2.8.4-denial-of-service-via-attributes · [email protected]
EPSS history
Timeline
  • 09 SEP 03:20Z
    EPSS moved — → 0%
    epss
  • 07 SEP 12:53Z
    commonmark 1.5.0 before 2.8.4 Denial of Service via Attributes
    cvelistv5