league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. 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.
History

Thu, 08 Oct 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 07 Sep 2026 13:00:00 +0000

Type Values Removed Values Added
Description league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. 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.
Title league/commonmark before 2.9.1 Denial of Service via parsing
First Time appeared Thephpleague
Thephpleague commonmark
Weaknesses CWE-407
CPEs cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*
Vendors & Products Thephpleague
Thephpleague commonmark
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-09-07T12:53:50.575Z

Updated: 2026-10-08T15:25:52.185Z

Reserved: 2026-09-07T12:34:31.457Z

Link: CVE-2026-86430

cve-icon Vulnrichment

Updated: 2026-09-09T14:31:12.903Z

cve-icon NVD

Status : Analyzed

Published: 2026-09-07T13:20:42.320

Modified: 2026-10-08T16:17:57.177

Link: CVE-2026-86430

cve-icon Redhat

No data.