CVE-2023-37463: Quadratic complexity bugs may lead to a denial of service

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-07-13 · updated 2026-06-17
Weakness: CWE-400

Description

cmark-gfm is an extended version of the C reference implementation of CommonMark, a rationalized version of Markdown syntax with a spec. Three polynomial time complexity issues in cmark-gfm may lead to unbounded resource exhaustion and subsequent denial of service. These vulnerabilities have been patched in 0.29.0.gfm.12.

Affected products

github cmark-gfm: before 0.29.0.gfm.12 — fixed in 0.29.0.gfm.12

How to fix

Upgrade to a fixed version: github cmark-gfm 0.29.0.gfm.12. Check the vendor advisory for mitigations.

References

https://github.com/github/cmark-gfm/releases/tag/0.29.0.gfm.12
https://github.com/github/cmark-gfm/security/advisories/GHSA-w4qg-3vf7-m9x5
https://github.com/github/cmark-gfm/releases/tag/0.29.0.gfm.12
https://github.com/github/cmark-gfm/security/advisories/GHSA-w4qg-3vf7-m9x5

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