league/commonmark from 2.0.0 before 2.10.2 contains a quadratic-time denial of service vulnerability in the GitHub Flavored Markdown Table extension's TableStartParser::tryStart() block-start scan. Unauthenticated attackers can submit a large paragraph of pipe-free lines not starting with letters, forcing repeated full-buffer strpos scans that exhaust PHP worker CPU.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation poc

Automatable yes

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
thephpleague commonmark unaffected
Version Status Constraints
2.0.0 affected < 2.10.2
2.10.2 unaffected —

No data.

No data.

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Project Subscriptions

Vendors Products
Thephpleague Subscribe
Commonmark Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/thephpleague/commonmark/security/advisories/GHSA-3q6v-r5mr-hxv8 cve-icon cve-icon cve-icon
https://www.vulncheck.com/advisories/league-commonmark-2.0.0-before-2.10.2-quadratic-dos-via-tablestartparser cve-icon cve-icon
History

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

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 08 Oct 2026 14:15:00 +0000

Type Values Removed Values Added
Description league/commonmark from 2.0.0 before 2.10.2 contains a quadratic-time denial of service vulnerability in the GitHub Flavored Markdown Table extension's TableStartParser::tryStart() block-start scan. Unauthenticated attackers can submit a large paragraph of pipe-free lines not starting with letters, forcing repeated full-buffer strpos scans that exhaust PHP worker CPU.
Title league/commonmark 2.0.0 before 2.10.2 Quadratic DoS via TableStartParser
First Time appeared Thephpleague
Thephpleague commonmark
Weaknesses CWE-400
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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-08T17:03:50.815Z

Reserved: 2026-10-05T21:59:09.591Z

Link: CVE-2026-105830

cve-icon Vulnrichment

Updated: 2026-10-08T17:03:25.566Z

cve-icon NVD

Status : Received

Published: 2026-10-08T15:17:35.340

Modified: 2026-10-08T17:17:12.843

Link: CVE-2026-105830

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-08T16:00:06Z

Weaknesses