CVE-2023-26485: Quadratic complexity may lead to a denial of service in cmark-gfm
First published: Fri Mar 31 2023(Updated: )
cmark-gfm is GitHub's fork of cmark, a CommonMark parsing and rendering library and program in C. A polynomial time complexity issue in cmark-gfm may lead to unbounded resource exhaustion and subsequent denial of service. This CVE covers quadratic complexity issues when parsing text which leads with either large numbers of `_` characters. This issue has been addressed in version 0.29.0.gfm.10. Users are advised to upgrade. Users unable to upgrade should validate that their input comes from trusted sources. ### Impact A polynomial time complexity issue in cmark-gfm may lead to unbounded resource exhaustion and subsequent denial of service. ### Proof of concept ``` $ ~/cmark-gfm$ python3 -c 'pad = "_" * 100000; print(pad + "." + pad, end="")' | time ./build/src/cmark-gfm --to plaintext ``` Increasing the number 10000 in the above commands causes the running time to increase quadratically. ### Patches This vulnerability have been patched in 0.29.0.gfm.10. ### Note on cmark and cmark-gfm XXX: TBD [cmark-gfm](https://github.com/github/cmark-gfm) is a fork of [cmark](https://github.com/commonmark/cmark) that adds the GitHub Flavored Markdown extensions. The two codebases have diverged over time, but share a common core. These bugs affect both `cmark` and `cmark-gfm`. ### Credit We would like to thank @gravypod for reporting this vulnerability. ### References 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)
Credit: security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Github Cmark-gfm | <0.29.0.gfm.10 |
Never miss a vulnerability like this again
Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.
Reference Links
Frequently Asked Questions
What is CVE-2023-26485?
CVE-2023-26485 is a vulnerability in cmark-gfm, a CommonMark parsing and rendering library and program in C, which may lead to denial of service due to unbounded resource exhaustion.
What is the severity of CVE-2023-26485?
The severity of CVE-2023-26485 is high with a CVSS score of 7.5.
How does CVE-2023-26485 impact cmark-gfm?
CVE-2023-26485 introduces a polynomial time complexity issue when parsing text, which can result in unbounded resource usage and subsequent denial of service.
Which versions of cmark-gfm are affected by CVE-2023-26485?
Versions up to and excluding 0.29.0.gfm.10 of cmark-gfm are affected by CVE-2023-26485.
Is there a fix for CVE-2023-26485?
Yes, a fix for CVE-2023-26485 has been implemented. It is recommended to update to a version of cmark-gfm that includes the fix.
- collector/nvd-index
- agent/references
- agent/weakness
- agent/type
- agent/softwarecombine
- collector/mitre-cve
- source/MITRE
- agent/title
- agent/remedy
- agent/severity
- agent/last-modified-date
- agent/author
- agent/description
- agent/first-publish-date
- agent/event
- agent/tags
- vendor/github
- canonical/github cmark-gfm