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Not in CISA KEV
HIGH severity

CVE-2022-21211 — posix

HIGH

CVE-2022-21211 is a high-severity (CVSS 7.5) CWE-252 vulnerability in posix. 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.

Unhandled crash in npm posix

Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Oct 29, 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 CVEs64th percentile — riskier than 64% of all scored CVEsHighest risk
0.00%0.51%1.03%1.54%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

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

69other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
posixnpm
3Kdownloads / week

Description

This affects all versions of package posix. When invoking the toString method, it will fallback to 0x0 value, as the value of toString is not invokable (not a function), and then it will crash with type-check.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmposixall versionsNo fix

Affected Products

1 product · 1 configurations
Application
posixposix_project
all
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.

This affects all versions of package posix. When invoking the toString m…

snyk.ioNVDJun 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for posix, 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 posix for CVE-2022-21211. 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

This affects all versions of package posix. When invoking the toString method, it will fallback to 0x0 value, as the value of toString is not invokable (not a function), and then it will crash with type-check.
O3 Security · Impact-Aware SCA

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CVE-2022-21211: posix: Unhandled crash in npm posix