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Unratedamended

Sandbox Breakout / Arbitrary Code Execution in localeval

GHSA-mmqv-m45h-q2hp

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (localeval 15.3.0), redeploy, then verify what is actually installed.

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

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

All versions of localeval are vulnerable to Sandbox Escape leading to Remote Code Execution. The package fails to restrict access to the main context through constructor.constructor. This may allow attackers to execute arbitrary code in the system. Evaluating the payload returns the contents of process.env. Recommendation No fix is currently available. Consider using an alternative package until a fix is made available.

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

    Amended from ghsa record GHSA-mmqv-m45h-q2hp

  2. Revision 1 · created ·

    Published from osv record GHSA-mmqv-m45h-q2hp

Agent brief

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

# Patch Next advisory brief: GHSA-mmqv-m45h-q2hp

Advisory: Sandbox Breakout / Arbitrary Code Execution in localeval
IDs: GHSA-mmqv-m45h-q2hp
Record: https://patchnext.com/advisories/ghsa-mmqv-m45h-q2hp (revision 2, source checked 26 Oct 2026, 12:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: localeval 15.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm localeval: affected < 15.3.0; fixed in 15.3.0

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on localeval.
- 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-mmqv-m45h-q2hp (OSV record GHSA-mmqv-m45h-q2hp lists affected ranges: npm localeval >=0 <15.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-mmqv-m45h-q2hp (GitHub-reviewed advisory GHSA-mmqv-m45h-q2hp lists affected ranges: npm localeval >=0 <15.3.0)

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