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High, CVSS 7.5amended

Unhandled crash in npm posix

CVE-2022-21211GHSA-27mx-gchc-6xjp

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm posix

    Affected
    <= 4.2.0
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2022-21211: 1.06% estimated exploitation activity in the next 30 days; percentile 64.62 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-27mx-gchc-6xjp

  2. Revision 1 · created ·

    Published from osv record GHSA-27mx-gchc-6xjp

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2022-21211

Advisory: Unhandled crash in npm posix
IDs: CVE-2022-21211, GHSA-27mx-gchc-6xjp
Record: https://patchnext.com/advisories/cve-2022-21211 (revision 2, source checked 26 Oct 2026, 12:16 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm posix: affected <= 4.2.0

## Suggested inspection (read-only)
- `npm ls posix --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on posix.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-27mx-gchc-6xjp (OSV record GHSA-27mx-gchc-6xjp lists affected ranges: npm posix >=0 <=4.2.0)
- Verified: https://github.com/advisories/GHSA-27mx-gchc-6xjp (GitHub-reviewed advisory GHSA-27mx-gchc-6xjp lists affected ranges: npm posix >=0 <=4.2.0)

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