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

Summary

### Impact CommonMarker uses `cmark-gfm` for rendering [Github Flavored Markdown](https://github.github.com/gfm/). 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/Time_complexity ### For more information If you have any questions or comments about this advisory: * Open an issue in [github/cmark-gfm](https://github.com/github/cmark-gfm) ### Acknowledgements We would like to thank [Legit Security](https://www.legitsecurity.com) for reporting this vulnerability.