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Unbounded resource exhaustion in cmark-gfm autolink extension may lead to denial of service

GHSA-4qw4-jpp4-8gvp

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (commonmarker 0.23.6), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

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. Patches This vulnerability has been patched in the following CommonMarker release: - v0.23.6 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/Timecomplexity 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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-4qw4-jpp4-8gvp

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-4qw4-jpp4-8gvp

Advisory: Unbounded resource exhaustion in cmark-gfm autolink extension may lead to denial of service
IDs: GHSA-4qw4-jpp4-8gvp
Record: https://patchnext.com/advisories/ghsa-4qw4-jpp4-8gvp (revision 1, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: commonmarker 0.23.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems commonmarker: affected < 0.23.6; fixed in 0.23.6

## Suggested inspection (read-only)
- RubyGems commonmarker: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on commonmarker.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4qw4-jpp4-8gvp (GitHub-reviewed advisory GHSA-4qw4-jpp4-8gvp lists affected ranges: RubyGems commonmarker >=0 <0.23.6)

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