Unsound LowRUSTSEC-2025-0023 · tokio
RUSTSEC-2025-0023: Broadcast channel calls clone in parallel, but does not require `Sync`
Short answertokio has an API that can cause undefined behaviour from safe code: Broadcast channel calls clone in parallel, but does not require `Sync`. Fixed in 1.38.2, 1.42.1, 1.43.1, 1.44.2.
| Crate | tokio |
|---|---|
| Type | Unsound (memory-corruption) |
| Affected versions | From 0.2.5 before 1.38.2; from 1.39.0 before 1.42.1; from 1.43.0 before 1.43.1; from 1.44.0 before 1.44.2. |
| Fixed in | 1.38.2, 1.42.1, 1.43.1, 1.44.2 |
| Severity | Low (GitHub rating) |
| Published | 2025-04-07 |
| Last changed | 2025-10-28 |
| Also known as | GHSA-rr8g-9fpq-6wmg |
What to do
- See which version you have:
cargo tree -i tokio(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p tokio. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for exampletokio = "1.44.2") 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
The broadcast channel internally calls clone on the stored value when receiving it, and only requires T:Send. This means that using the broadcast channel with values that are Send but not Sync can trigger unsoundness if the clone implementation makes use of the value being !Sync.
Thank you to Austin Bonander for finding and reporting this issue.
References
- Package: crates.io/crates/tokio
- Advisory: rustsec.org/advisories/RUSTSEC-2025-0023.html
- Web: github.com/tokio-rs/tokio/pull/7232
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Other advisories for tokio
- VulnerabilityRUSTSEC-2021-0072 · 2021-07-07Task dropped in wrong thread when aborting `LocalSet` task
- VulnerabilityRUSTSEC-2021-0124 · 2021-11-16Data race when sending and receiving after closing a `oneshot` channel
- VulnerabilityRUSTSEC-2023-0001 · 2023-01-04reject_remote_clients Configuration corruption
- UnsoundRUSTSEC-2023-0005 · 2023-01-11`tokio::io::ReadHalf<T>::unsplit` is Unsound
- VulnerabilityRUSTSEC-2026-0384 · 2026-10-21Race condition in `tokio::time::Interval` on Tokio v1.54.0
- UnsoundRUSTSEC-2026-0386 · 2026-10-13`AsyncFd::new` and related constructors violate I/O safety
Up next
Same cratetokio: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?