How severe is CVE-2020-35915?

CVE-2020-35915 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-35915?

CVE-2020-35915 affects the following packages: futures-intrusive (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2020-35915?

Update futures-intrusive to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35915 is resolved across your whole dependency graph.

How do I detect CVE-2020-35915 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for futures-intrusive. 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 CVE-2020-35915 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 CVE-2020-35915?

O3 pinpoints whether CVE-2020-35915 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 CVE-2020-35915 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2020-35915, 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.

When was CVE-2020-35915 published, and has it been updated?

CVE-2020-35915 was published on August 25, 2021 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

Not in CISA KEV

MEDIUM severity

CVE-2020-35915

MEDIUM

CVE-2020-35915 is a medium-severity (CVSS 5.5) vulnerability in futures-intrusive. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2020-35915 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Data races in futures-intrusive

Also known asRUSTSEC-2020-0072

Published

Aug 25, 2021

Updated

Nov 8, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 8, 2023 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🦀futures-intrusive

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

This is a soundness issue and allows data races, potentially leading to crashes and segfaults from safe Rust code.

The flaw was corrected by adding a T: Send + Sync bound for GenericMutexGuard's Sync trait.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`futures-intrusive`	all versions	0.4.0

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-intrusive crate before 0.4.0 for …

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-intrusive. 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-intrusive to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35915 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 CVE-2020-35915 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 CVE-2020-35915. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

GenericMutexGuard<T> was given the Sync auto trait as long as T is Send due to its contained members. However, since the guard is supposed to represent an acquired lock and allows concurrent access to the underlying data from different threads, it should only be Sync when the underlying data is. This is a soundness issue and allows data races, potentially leading to crashes and segfaults from safe Rust code. The flaw was corrected by adding a T: Send + Sync bound for GenericMutexGuard's Sync trait.

O3 Security · Impact-Aware SCA

Is CVE-2020-35915 in your dependencies?

O3 detects CVE-2020-35915 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.

Scan my dependencies How O3 SCA works