CVE-2020-35906: futures_task::waker may cause a use-after-free if used on a type that isn't 'static

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-12-31 · updated 2026-06-17
Weakness: CWE-416

Description

An issue was discovered in the futures-task crate before 0.3.6 for Rust. futures_task::waker may cause a use-after-free in a non-static type situation.

Affected products

rust-lang Futures-Task: from 0.2.1 before 0.3.6 — fixed in 0.3.6
Crates.Io Futures-Task: from 0.2.2-0 before 0.3.6 — fixed in 0.3.6

How to fix

Upgrade to a fixed version: rust-lang Futures-Task 0.3.6; Crates.Io Futures-Task 0.3.6. Check the vendor advisory for mitigations.

References

https://rustsec.org/advisories/RUSTSEC-2020-0060.html
https://rustsec.org/advisories/RUSTSEC-2020-0060.html

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