Function grcov::covdir::get_coverage uses the unsafe function get_unchecked_mut without validating that the index is in bounds.

This results in memory corruption, and could potentially allow arbitrary code execution provided that an attacker can feed the tool crafted coverage data.

References

• mozilla/grcov@c821956
• https://bugzilla.mozilla.org/show_bug.cgi?id=1917475
• https://rustsec.org/advisories/RUSTSEC-2025-0005.html