CVE-2020-35905: MutexGuard::map can cause a data race in safe code

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-12-31 · updated 2026-06-17
Weakness: CWE-362

Description

An issue was discovered in the futures-util crate before 0.3.7 for Rust. MutexGuard::map can cause a data race for certain closure situations (in safe code).

Affected products

rust-lang Future-Utils: before 0.3.7 — fixed in 0.3.7
Crates.Io Futures-Util: from 0.3.2 before 0.3.7 — fixed in 0.3.7

How to fix

Upgrade to a fixed version: rust-lang Future-Utils 0.3.7; Crates.Io Futures-Util 0.3.7. Check the vendor advisory for mitigations.

References

https://rustsec.org/advisories/RUSTSEC-2020-0059.html
https://rustsec.org/advisories/RUSTSEC-2020-0059.html

Get alerted when CVE-2020-35905 or the next vulnerability affects your stack