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.