RUSTSEC-2020-0094: Unsound: can make `ARefss` contain a !Send, !Sync object.

What to do

1. See which version you have: cargo tree -i reffers (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p reffers. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example reffers = "0.6.1") 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

ARefss<'a, V> is a type that is assumed to contain objects that are Send + Sync.

In the affected versions of this crate, Send/Sync traits are unconditionally implemented for ARefss<'a, V>.

By using the ARefss::map() API, we can insert a !Send or !Sync object into ARefss<'a, V>. After that, it is possible to create a data race to the inner object of ARefss<'a, V>, which can lead to undefined behavior & memory corruption.

The flaw was corrected in commit 6dd7ca0 (https://github.com/diwic/reffers-rs/commit/6dd7ca0d50f2464df708975cdafcfaeeb6d41c66) by adding trait bound V: Send + Sync to ARefss::map() API.

References

• Package: crates.io/crates/reffers
• Advisory: rustsec.org/advisories/RUSTSEC-2020-0094.html
• Report: github.com/diwic/reffers-rs/issues/7

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