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Not in CISA KEV
MEDIUM severity

CVE-2020-35908 — futures-util

MEDIUM

CVE-2020-35908 is a medium-severity (CVSS 5.5) vulnerability in futures-util. A fix is available for futures-util — see the affected versions and patch details below.

Improper `Sync` implementation on `FuturesUnordered` in futures-utils can cause data corruption

Also known asGHSA-5r9g-j7jj-hw6cRUSTSEC-2020-0062
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs28th percentile — riskier than 28% of all scored CVEsHighest risk
0.00%0.28%0.56%0.84%0.1%0.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🦀futures-util

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

An issue was discovered in the futures-util crate before 0.3.2 for Rust. FuturesUnordered can lead to data corruption because Sync is mishandled.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iofutures-util≥ 0.3.0&&< 0.3.20.3.2cargo update -p futures-util --precise 0.3.2

Affected Products

1 product · 1 configurations
Application
future-utilsrust-lang
< 0.3.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for futures-util, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update futures-util to 0.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35908 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

An issue was discovered in the futures-util crate before 0.3.2 for Rust. FuturesUnordered can lead to data corruption because Sync is mishandled.
O3 Security · Impact-Aware SCA

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CVE-2020-35908: futures-util — Fixed in 0.3.2