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

gjtorikian/commonmarker#190
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.

References

• GHSA-4qw4-jpp4-8gvp
• gjtorikian/commonmarker#190
• https://github.com/gjtorikian/commonmarker/releases/tag/v0.23.6