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VULNERABILITIES

CVE-2026-86430 Details

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.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:7.5 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://github.com/thephpleague/commonmark/security/advisories/GHSA-j8pm-gj4c-rq4x [email protected]MitigationVendor AdvisoryPatch
https://www.vulncheck.com/advisories/league-commonmark-before-2.9.1-denial-of-service-via-parsing [email protected]Third Party Advisory

Weakness Enumeration

CWE-IDCWE NameSource
CWE-407Inefficient Algorithmic Complexity[email protected]

Affected Products

ProductVersions
thephpleague commonmark
< 2.9.1

CPE

  • cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.

Change History

3 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-86430
NVD Published Date:
Sep 7, 2026
NVD Last Modified:
Sep 10, 2026
Source:
[email protected]
CVE-2026-86430 Details - Not Deferred