Rust advisories / beef
Vulnerability HighRUSTSEC-2020-0122 · beef
RUSTSEC-2020-0122: beef::Cow lacks a Sync bound on its Send trait allowing for data races
Short answerA security vulnerability in the beef crate: beef::Cow lacks a Sync bound on its Send trait allowing for data races. High severity (CVSS 8.1). Fixed in 0.5.0: update to a fixed version.
| Crate | beef |
|---|---|
| Type | Vulnerability (memory-corruption, thread-safety) |
| Affected versions | Before 0.5.0. |
| Fixed in | 0.5.0 |
| Severity | High, CVSS 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Published | 2020-10-28 |
| Last changed | 2023-11-08 |
| Also known as | CVE-2020-36442, GHSA-m7w4-8wp8-m2xq |
What to do
- See which version you have:
cargo tree -i beef(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p beef. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for examplebeef = "0.5.0") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
Affected versions of this crate did not have a T: Sync bound in the Send impl for Cow<'_, T, U>. This allows users to create data races by making Cow contain types that are (Send && !Sync) like Cell<_> or RefCell<_>.
Such data races can lead to memory corruption.
The flaw was corrected in commit d1c7658 by adding trait bounds T: Sync and T::Owned: Send to the Send impl for Cow<'_, T, U>.
References
- Package: crates.io/crates/beef
- Advisory: rustsec.org/advisories/RUSTSEC-2020-0122.html
- Report: github.com/maciejhirsz/beef/issues/37
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
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