RUSTSEC-2022-0041: Unsoundness of AtomicCell<*64> arithmetics on 32-bit targets that support Atomic*64

What to do

1. See which version you have: cargo tree -i crossbeam-utils (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p crossbeam-utils. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example crossbeam-utils = "0.8.7") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

Impact

Affected versions of this crate incorrectly assumed that the alignment of {i,u}64 was always the same as Atomic{I,U}64.

However, the alignment of {i,u}64 on a 32-bit target can be smaller than Atomic{I,U}64.

This can cause the following problems:

• Unaligned memory accesses
• Data race

Crates using fetch_* methods with AtomicCell<{i,u}64> are affected by this issue.

32-bit targets without Atomic{I,U}64 and 64-bit targets are not affected by this issue.

32-bit targets with Atomic{I,U}64 and {i,u}64 have the same alignment are also not affected by this issue.

The following is a complete list of the builtin targets that may be affected. (last update: nightly-2022-02-11)

• armv7-apple-ios (tier 3)
• armv7s-apple-ios (tier 3)
• i386-apple-ios (tier 3)
• i586-unknown-linux-gnu
• i586-unknown-linux-musl
• i686-apple-darwin (tier 3)
• i686-linux-android
• i686-unknown-freebsd
• i686-unknown-haiku (tier 3)
• i686-unknown-linux-gnu
• i686-unknown-linux-musl
• i686-unknown-netbsd (tier 3)
• i686-unknown-openbsd (tier 3)
• i686-wrs-vxworks (tier 3)

(script to get list)

Patches

This has been fixed in crossbeam-utils 0.8.7.

Affected 0.8.x releases have been yanked.

Thanks to @taiki-e.

References

• Package: crates.io/crates/crossbeam-utils
• Advisory: rustsec.org/advisories/RUSTSEC-2022-0041.html
• Web: github.com/crossbeam-rs/crossbeam/pull/781

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.