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HIGH severity

CVE-2021-31996 — algorithmica

HIGH

CVE-2021-31996 is a high-severity (CVSS 7.5) CWE-415 vulnerability in algorithmica. No vendor fix is recorded yet; mitigation options are listed below.

Double free in algorithmica

Also known asRUSTSEC-2021-0053
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.0%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs61th percentile — riskier than 61% of all scored CVEsHighest risk
0.00%0.49%0.97%1.46%0.4%1.0%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-31996 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 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
🦀algorithmica

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 algorithmica crate through 2021-03-07 for Rust. In the affected versions of this crate, merge_sort::merge() wildly duplicates and drops ownership of T without guarding against double-free. Due to such implementation, simply invoking merge_sort::merge() on Vec<T: Drop> can cause double free bugs.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🦀crates.ioalgorithmicaall versionsNo fix

Affected Products

1 product · 1 configurations
Application
algorithmicaalgorithmica_project
≤ 2021-03-07
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 algorithmica, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of algorithmica has shipped for CVE-2021-31996 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    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 algorithmica crate through 2021-03-07 for Rust. In the affected versions of this crate, `merge_sort::merge()` wildly duplicates and drops ownership of `T` without guarding against double-free. Due to such implementation, simply invoking `merge_sort::merge()` on `Vec<T: Drop>` can cause **double free** bugs.
O3 Security · Impact-Aware SCA

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CVE-2021-31996: algorithmica (High 7.5)