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CRITICAL severity

CVE-2020-35895 — stack

CRITICALFix: arcnmx/stack-rs@369e557

CVE-2020-35895 is a critical-severity (CVSS 9.8) Out-of-bounds Write vulnerability in stack. A fix is available for stack — see the affected versions and patch details below.

Out-of-bounds write in stack

Also known asGHSA-h45v-vgvp-3h5vRUSTSEC-2020-0042
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk
0.13%0.88%1.62%2.37%0.6%1.9%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2020-35895 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 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
🦀stack

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

ArrayVec::insert allows insertion of an element into the array object into the specified index. Due to a missing check on the upperbound of this index, it is possible to write out of bounds.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iostackall versions0.3.1cargo update -p stack --precise 0.3.1

Affected Products

1 product · 1 configurations
Application
stackstack_project
< 0.3.1
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 stack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update stack to 0.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35895 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

ArrayVec::insert allows insertion of an element into the array object into the specified index. Due to a missing check on the upperbound of this index, it is possible to write out of bounds.
O3 Security · Impact-Aware SCA

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CVE-2020-35895: stack — Fixed in 0.3.1