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Not in CISA KEV
HIGH severity

CVE-2020-35711 — arc-swap

HIGH

CVE-2020-35711 is a high-severity (CVSS 7.5) vulnerability in arc-swap. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for arc-swap — see the affected versions and patch details below.

Dangling reference in `access::Map` with Constant

Also known asGHSA-9pqx-g3jh-qpqqRUSTSEC-2020-0091
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
1 known
Exploitation data as of Oct 28, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs76th percentile — riskier than 76% of all scored CVEsHighest risk
0.00%0.71%1.41%2.12%0.3%1.6%Apr 26Aug 26Oct 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

2 pkgs affected
🦀arc-swap🦀arc-swap

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 has been discovered in the arc-swap crate before 0.4.8 (and 1.x before 1.1.0) for Rust. Use of arc_swap::access::Map with the Constant test helper (or with a user-supplied implementation of the Access trait) could sometimes lead to dangling references being returned by the map.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.ioarc-swap≥ 0.4.2&&< 0.4.80.4.8cargo update -p arc-swap --precise 0.4.8
🦀crates.ioarc-swap≥ 1.0.0&&< 1.1.01.1.0cargo update -p arc-swap --precise 1.1.0

Affected Products

1 product · 2 configurations
Application
arc-swaparc-swap_project
≥ 1.0.0 && < 1.1.0
range
Exploits & PoCs
1

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 has been discovered in the arc-swap crate before 0.4.8 (and 1.x…

github.comNVDDec 2020

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update arc-swap to 0.4.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35711 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 has been discovered in the arc-swap crate before 0.4.8 (and 1.x before 1.1.0) for Rust. Use of arc_swap::access::Map with the Constant test helper (or with a user-supplied implementation of the Access trait) could sometimes lead to dangling references being returned by the map.
O3 Security · Impact-Aware SCA

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CVE-2020-35711: arc-swap — Fixed in 0.4.8