How severe is GHSA-rh4w-94hh-9943?

GHSA-rh4w-94hh-9943 has a CVSS score of 4.7/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-rh4w-94hh-9943?

GHSA-rh4w-94hh-9943 affects the following packages: futures-util (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-rh4w-94hh-9943?

Update futures-util to 0.3.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rh4w-94hh-9943 is resolved across your whole dependency graph.

How do I detect GHSA-rh4w-94hh-9943 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for futures-util. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-rh4w-94hh-9943 if there is no patch (or I can't update yet)?

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.

How does O3 Security protect against GHSA-rh4w-94hh-9943?

O3 pinpoints whether GHSA-rh4w-94hh-9943 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-rh4w-94hh-9943 actively exploited in the wild?

Yes. There are 1 known exploit references for GHSA-rh4w-94hh-9943, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-rh4w-94hh-9943?

GHSA-rh4w-94hh-9943 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 17th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-rh4w-94hh-9943?

GHSA-rh4w-94hh-9943 is classified as CWE-362 (CWE-362). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-rh4w-94hh-9943 published, and has it been updated?

GHSA-rh4w-94hh-9943 was published on May 24, 2022 and was last updated on November 8, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀 crates.io

GHSA-rh4w-94hh-9943

MEDIUM

MutexGuard::map can cause a data race in safe code

Also known asCVE-2020-35905RUSTSEC-2020-0059

Published

May 24, 2022

Updated

Nov 8, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk17th percentile+0.21%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

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

Affected versions of the crate had a Send/Sync implementation for MappedMutexGuard that only considered variance on T, while MappedMutexGuard dereferenced to U.

This could of led to data races in safe Rust code when a closure used in MutexGuard::map() returns U that is unrelated to T.

The issue was fixed by fixing Send and Sync implementations, and by adding a PhantomData<&'a mut U> marker to the MappedMutexGuard type to tell the compiler that the guard is over U too.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`futures-util`	≥ 0.3.2&&< 0.3.7	0.3.7

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

An issue was discovered in the futures-util crate before 0.3.7 for Rust.…

rustsec.orgNVDJan 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for futures-util. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update futures-util to 0.3.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rh4w-94hh-9943 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-rh4w-94hh-9943 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-rh4w-94hh-9943. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Affected versions of the crate had a Send/Sync implementation for MappedMutexGuard that only considered variance on T, while MappedMutexGuard dereferenced to U. This could of led to data races in safe Rust code when a closure used in MutexGuard::map() returns U that is unrelated to T. The issue was fixed by fixing Send and Sync implementations, and by adding a PhantomData<&'a mut U> marker to the MappedMutexGuard type to tell the compiler that the guard is over U too.

O3 Security · Impact-Aware SCA

Is GHSA-rh4w-94hh-9943 in your dependencies?

O3 detects GHSA-rh4w-94hh-9943 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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