CVE-2023-22486: cmark-gfm Quadratic complexity bug in handle_close_bracket may lead to a denial of service

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-01-26 · updated 2026-06-17
Weakness: CWE-400

Description

cmark-gfm is GitHub's fork of cmark, a CommonMark parsing and rendering library and program in C. Versions prior to 0.29.0.gfm.7 contain a polynomial time complexity issue in handle_close_bracket that may lead to unbounded resource exhaustion and subsequent denial of service. This vulnerability has been patched in 0.29.0.gfm.7.

Affected products

github cmark-gfm: before 0.29.0.gfm.7 — fixed in 0.29.0.gfm.7

How to fix

Upgrade to a fixed version: github cmark-gfm 0.29.0.gfm.7. Check the vendor advisory for mitigations.

References

https://github.com/github/cmark-gfm/security/advisories/GHSA-r572-jvj2-3m8p
https://github.com/github/cmark-gfm/security/advisories/GHSA-r572-jvj2-3m8p

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