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MEDIUM severity

CVE-2021-25901 — lazy-init

MEDIUM

CVE-2021-25901 is a medium-severity (CVSS 5.3) Out-of-bounds Read vulnerability in lazy-init. A fix is available for lazy-init — see the affected versions and patch details below.

Out of bounds read in lazy-init

Also known asRUSTSEC-2021-0004
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs70th percentile — riskier than 70% of all scored CVEsHighest risk
0.00%0.60%1.21%1.81%0.3%1.3%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-25901 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
🦀lazy-init

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 lazy-init crate through 2021-01-17 for Rust. Lazy lacks a Send bound, leading to a data race.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iolazy-initall versions0.4.0cargo update -p lazy-init --precise 0.4.0

Affected Products

1 product · 1 configurations
Application
lazy-initlazy-init_project
≤ 0.4.0
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 lazy-init, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update lazy-init to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25901 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 lazy-init crate through 2021-01-17 for Rust. Lazy lacks a Send bound, leading to a data race.
O3 Security · Impact-Aware SCA

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CVE-2021-25901: lazy-init — Fixed in 0.4.0