CVE-2023-22485: GitHub Cmark-Gfm

Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days.

cmark-gfm is GitHub's fork of cmark, a CommonMark parsing and rendering library and program in C. In versions prior 0.29.0.gfm.7, a crafted markdown document can trigger an out-of-bounds read in the `validate_protocol` function. We believe this bug is harmless in practice, because the out-of-bounds read accesses `malloc` metadata without causing any visible damage.This vulnerability has been patched in 0.29.0.gfm.7.

Affected products

• GitHub Cmark-Gfm: before 0.29.0.gfm.7 (fixed in 0.29.0.gfm.7)

Published 2023-01-24. Last modified 2026-06-17.