Summary
Unbounded resource exhaustion in cmark-gfm autolink extension may lead to denial of service
Workarounds
Disable use of the autolink extension.
References
https://github.com/gjtorikian/commonmarker/pull/190
https://github.com/github/cmark-gfm/security/advisories/GHSA-cgh3-p57x-9q7q
https://en.wikipedia.org/wiki/Time_complexity
For more information
If you have any questions or comments about this advisory:
- Open an issue in github/cmark-gfm
Acknowledgements
We would like to thank Legit Security for reporting this vulnerability.
Impact
CommonMarker uses cmark-gfm for rendering Github Flavored Markdown. A polynomial time complexity issue in cmark-gfm's autolink extension may lead to unbounded resource exhaustion and subsequent denial of service.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This vulnerability has been patched in the following CommonMarker release:
- v0.23.6
Frequently Asked Questions
- What is GHSA-4QW4-JPP4-8GVP? GHSA-4QW4-JPP4-8GVP is a medium-severity uncontrolled resource consumption vulnerability in commonmarker (rubygems), affecting versions < 0.23.6. It is fixed in 0.23.6. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- Which versions of commonmarker are affected by GHSA-4QW4-JPP4-8GVP? commonmarker (rubygems) versions < 0.23.6 is affected.
- Is there a fix for GHSA-4QW4-JPP4-8GVP? Yes. GHSA-4QW4-JPP4-8GVP is fixed in 0.23.6. Upgrade to this version or later.
- Is GHSA-4QW4-JPP4-8GVP exploitable, and should I be worried? Whether GHSA-4QW4-JPP4-8GVP is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-4QW4-JPP4-8GVP is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-4QW4-JPP4-8GVP? Upgrade
commonmarkerto 0.23.6 or later.