commonmark versions from 2.0.0 before 2.8.4 contain a denial of service vulnerability in XmlRenderer that emits depth-proportional indentation for every XML tag. Attackers can provide deeply nested Markdown or AST structures to cause quadratic memory consumption and output amplification, exhausting server resources.

Metrics

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 Low

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 Low

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Thephpleague Subscribe
Commonmark Subscribe

No data.

No data.

No data.

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-mj63-m3rc-8ppr cve-icon cve-icon
https://www.vulncheck.com/advisories/commonmark-2.0.0-before-2.8.4-denial-of-service-via-xml cve-icon cve-icon
History

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

Type Values Removed Values Added
Description commonmark versions from 2.0.0 before 2.8.4 contain a denial of service vulnerability in XmlRenderer that emits depth-proportional indentation for every XML tag. Attackers can provide deeply nested Markdown or AST structures to cause quadratic memory consumption and output amplification, exhausting server resources.
Title commonmark 2.0.0 before 2.8.4 Denial of Service via XML
First Time appeared Thephpleague
Thephpleague commonmark
Weaknesses CWE-405
CPEs cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*
Vendors & Products Thephpleague
Thephpleague commonmark
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-07T12:53:51.897Z

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

Link: CVE-2026-86432

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-07T13:20:42.600

Modified: 2026-09-07T13:20:42.600

Link: CVE-2026-86432

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses