CVE-2023-26485 (High) detected in commonmarker-0.17.7.1.gem #49

Vulnerable Library - commonmarker-0.17.7.1.gem

A fast, safe, extensible parser for CommonMark. This wraps the official libcmark library.

Library home page: https://rubygems.org/gems/commonmarker-0.17.7.1.gem

Dependency Hierarchy:

• github-pages-175.gem (Root Library)
  • jekyll-commonmark-ghpages-0.1.3.gem
    • ❌ commonmarker-0.17.7.1.gem (Vulnerable Library)

Found in base branch: master

Vulnerability Details

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 is a fork of 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

Publish Date: 2023-03-31

URL: CVE-2023-26485

CVSS 3 Score Details (7.5)

Base Score Metrics:

• Exploitability Metrics:
  • Attack Vector: Network
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: None
  • Scope: Unchanged
• Impact Metrics:
  • Confidentiality Impact: None
  • Integrity Impact: None
  • Availability Impact: High

Suggested Fix

Type: Upgrade version

Origin: GHSA-48wp-p9qv-4j64

Release Date: 2023-03-31

Fix Resolution: commonmarker - 0.23.9