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CRITICAL severity

CVE-2020-35898 — actix-utils

CRITICALFix: actix/actix-net@0dca1a7

CVE-2020-35898 is a critical-severity (CVSS 9.1) Use After Free vulnerability in actix-utils. 1 public exploit reference exists, so weaponization risk is real. A fix is available for actix-utils — see the affected versions and patch details below.

Use after free in actix-utils

Also known asRUSTSEC-2020-0045
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk
0.00%0.64%1.29%1.93%0.3%1.4%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2020-35898 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀actix-utils

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 actix-utils crate before 2.0.0 for Rust. The Cell implementation allows obtaining more than one mutable reference to the same data.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.ioactix-utilsall versions2.0.0cargo update -p actix-utils --precise 2.0.0

Affected Products

1 product · 1 configurations
Application
actix-utilsactix
< 2.0.0
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 was discovered in the actix-utils crate before 2.0.0 for Rust. …

rustsec.orgNVDJan 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update actix-utils to 2.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35898 is resolved across your whole dependency graph.

  3. Workarounds

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

An issue was discovered in the actix-utils crate before 2.0.0 for Rust. The Cell implementation allows obtaining more than one mutable reference to the same data.
O3 Security · Impact-Aware SCA

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CVE-2020-35898: actix-utils — Fixed in 2.0.0