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MEDIUM severity

CVE-2021-26954 — qwutils

MEDIUMFix: qwertz19281/rust_utils@20cb73d

CVE-2021-26954 is a medium-severity (CVSS 5.3) CWE-415 vulnerability in qwutils. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for qwutils — see the affected versions and patch details below.

insert_slice_clone can double drop if Clone panics.

Also known asRUSTSEC-2021-0018
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk+0.02%
Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk
0.00%0.63%1.25%1.88%0.4%1.4%May 26Sep 26Nov 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

1 pkg affected
🦀qwutils

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 this crate used ptr::copy when inserting into the middle of a Vec. When ownership was temporarily duplicated during this copy, it calls the clone method of a user provided element.

This issue can result in an element being double-freed if the clone call panics.

Commit 20cb73d fixed this issue by adding a set_len(0) call before operating on the vector to avoid dropping the elements during a panic.

Affected Packages

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

Affected Products

1 product · 1 configurations
Application
qwutilsqwutils_project
< 0.3.1
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 qwutils crate before 0.3.1 for Rust. When…

rustsec.orgNVDFeb 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 qwutils, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update qwutils to 0.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-26954 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

Affected versions of this crate used ptr::copy when inserting into the middle of a Vec. When ownership was temporarily duplicated during this copy, it calls the clone method of a user provided element. This issue can result in an element being double-freed if the clone call panics. Commit `20cb73d` fixed this issue by adding a set_len(0) call before operating on the vector to avoid dropping the elements during a panic.
O3 Security · Impact-Aware SCA

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CVE-2021-26954: qwutils — Fixed in 0.3.1