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Not in CISA KEV
HIGH severity

CVE-2021-29938 — slice-deque

HIGH

CVE-2021-29938 is a high-severity (CVSS 7.5) CWE-415 vulnerability in slice-deque. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Double free in slice-deque

Also known asRUSTSEC-2021-0047
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk
0.00%0.56%1.12%1.68%0.4%1.2%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
🦀slice-deque

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 slice-deque crate through 2021-02-19 for Rust. A double drop can occur in SliceDeque::drain_filter upon a panic in a predicate function.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🦀crates.ioslice-dequeall versionsNo fix

Affected Products

1 product · 1 configurations
Application
slice-dequeslice-deque_project
≤ 2021-02-19
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 slice-deque crate through 2021-02-19 for …

rustsec.orgNVDApr 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 slice-deque, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of slice-deque for CVE-2021-29938. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    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 was discovered in the slice-deque crate through 2021-02-19 for Rust. A double drop can occur in SliceDeque::drain_filter upon a panic in a predicate function.
O3 Security · Impact-Aware SCA

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CVE-2021-29938: slice-deque (High 7.5)