P4Verified

CVE-2026-86430: commonmark before 2.9.1 (exclusive), 0.6.0 to before 2.9.1

CVE-2026-86430. CVSS 3.1 base score 7.5 (HIGH, Vendor/CNA). EPSS 0.00493 (percentile 0.40297), scored 2026-10-06.

Affected technology

commonmark · before 2.9.1 (exclusive)
thephpleague

commonmark · 0.6.0 to before 2.9.1
thephpleague

Description’s affected range: versions before 2.9.1

Component: Not specified by the source

Attack conditions (Vendor/CNA, CVSS 4.0): Network (remote) · No privileges required · No user interaction required

What an attacker can do

Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing. Vendor/CNA’s CVSS 4.0 assessment (base score 8.7/10) rates confidentiality and integrity impact as none; availability impact as high.

Published 2026-10-08 17:34:54.124553+00:00

CWE: CWE-407
CCR priority: 30.1 /100 (P4)
CVSS 3.1: 7.5 /10 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H · Vendor/CNA
EPSS: 0.00493 · percentile 0.40409 · 2026-10-08
KEV: no

Provenance

FIRST EPSS daily exploit-probability · Source record · observed 2026-10-08 17:36:22.845483+00:00 UTC
NVD CVE API 2.0 · Source record · observed 2026-10-08 17:32:11.049884+00:00 UTC

Stable permalink: https://cybercodered.org/item/cve-cve-2026-86430.html