GHSA-4q83-7cq4-p6wg RUSTSEC-2023-0005

`tokio::io::ReadHalf<T>::unsplit` is Unsound

Low crates.io

Severity: Low; The publisher's own rating, not a CVSS score
Exploit chance (EPSS): —; No score published
Known exploited: No; Not in CISA's catalog
Weakness: —; Not classified
Fix: 1.24.2; Upgrade tokio to this version or later

Description

tokio::io::ReadHalf<T>::unsplit can violate the Pin contract

The soundness issue is described in the tokio/issues#5372

Specific set of conditions needed to trigger an issue (a !Unpin type in ReadHalf) is unusual, combined with the difficulty of making any arbitrary use-after-free exploitable in Rust without doing a lot of careful alignment of data types in the surrounding code.

The tokio feature io-util is also required to be enabled to trigger this soundness issue.

Thanks to zachs18 reporting the issue to Tokio team responsibly and taiki-e and carllerche appropriately responding and fixing the soundness bug.

Tokio before 0.2.0 used futures 0.1 that did not have Pin, so it is not affected by this issue.

Affected versions

crates.io

Package	Vulnerable	Fixed in
tokio	`>= 1.21.0, < 1.24.2`	`1.24.2`
tokio	`>= 1.19.0, < 1.20.4`	`1.20.4`
tokio	`>= 0.2.0, < 1.18.5`	`1.18.5`
tokio	`>= 0.2.0, < 1.18.5` `>= 1.19.0, < 1.20.4` `>= 1.21.0, < 1.24.2`	`1.18.5` `1.20.4` `1.24.2`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

tokio crates.io → `1.24.2`

cargo

cargo update -p tokio --precise 1.24.2

References

Packages

Timeline

Jan 11, 2023 Published
Sep 10, 2026 Last updated by the source

Advisory	Severity	Why it's related
GHSA-5wjr-9356-4wc8 Tokio: Race condition in `tokio::time::Interval`	Medium	Also affects tokio
RUSTSEC-2026-0386 `AsyncFd::new` and related constructors violate I/O safety	Not rated yet	Also affects tokio
GHSA-rr8g-9fpq-6wmg Tokio broadcast channel calls clone in parallel, but does not require `Sync`	Low	Also affects tokio
GHSA-7rrj-xr53-82p7 Tokio reject_remote_clients configuration may get dropped when creating a Windows named pipe	Medium	Also affects tokio
RUSTSEC-2021-0124 Race Condition in tokio	High	Also affects tokio
RUSTSEC-2021-0072 Race condition in tokio	Medium	Also affects tokio

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