{"id":"CVE-2021-29939","aliases":["GHSA-9frf-r7c7-j2vg","RUSTSEC-2021-0048"],"url":"https://o3.security/vulnerability/CVE-2021-29939","summary":"Out of bounds write in stackvector","details":"StackVec::extend used the lower and upper bounds from an Iterator's size_hint to determine how many items to push into the stack based vector. If the size_hint implementation returned a lower bound that was larger than the upper bound, StackVec would write out of bounds and overwrite memory on the stack. As mentioned by the size_hint documentation, size_hint is mainly for optimization and incorrect implementations should not lead to memory safety issues.","published":"2021-04-01T05:15:14.843Z","modified":"2026-03-14T10:57:19.198142Z","cvss":{"score":7.3,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"crates.io","name":"stackvector","fixedVersion":"1.0.9"}],"fix":null,"references":[{"type":"EVIDENCE","url":"https://rustsec.org/advisories/RUSTSEC-2021-0048.html"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-29939"},{"type":"WEB","url":"https://github.com/Alexhuszagh/rust-stackvector/issues/2"},{"type":"PACKAGE","url":"https://github.com/Alexhuszagh/rust-stackvector"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-03-14T10:57:19.198142Z"}}