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CRITICAL severity

CVE-2021-30454 — outer_cgi

CRITICALFix: SolraBizna/outer_cgi@dd59b30

CVE-2021-30454 is a critical-severity (CVSS 9.8) Buffer Overflow vulnerability in outer_cgi. A fix is available for outer_cgi — see the affected versions and patch details below.

Uninitialized memory access in outer_cgi

Also known asRUSTSEC-2021-0051
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs65th percentile — riskier than 65% of all scored CVEsHighest risk
0.00%0.53%1.07%1.60%0.4%1.1%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-30454 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
🦀outer_cgi

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 outer_cgi crate before 0.2.1 for Rust. A user-provided Read instance receives an uninitialized memory buffer from KeyValueReader.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.ioouter_cgiall versions0.2.1cargo update -p outer_cgi --precise 0.2.1

Affected Products

1 product · 1 configurations
Application
outer cgiouter_cgi_project
< 0.2.1
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 outer_cgi, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update outer_cgi to 0.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-30454 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 outer_cgi crate before 0.2.1 for Rust. A user-provided Read instance receives an uninitialized memory buffer from KeyValueReader.
O3 Security · Impact-Aware SCA

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CVE-2021-30454: outer_cgi — Fixed in 0.2.1