Unratedamended

Regular Expression Denial of Service

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (esm 3.1.0), 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.

Add to your agent

Affected packages

npm esm
Affected
< 3.1.0
Fixed in
3.1.0

Sources

Open Source Vulnerabilities (OSV.dev), including the GitHub Advisory Database
OSV record GHSA-qx4v-6gc5-f2vv lists affected ranges: npm esm >=0 <3.1.0 (fixed)
VerifiedObserved 24 Oct 2026, 04:13 UTCStructured OSV record; GitHub-reviewed advisory.
GitHub Advisory Database and maintainer security advisories on GitHub
GitHub-reviewed advisory GHSA-qx4v-6gc5-f2vv lists affected ranges: npm esm >=0 <3.1.0
VerifiedObserved 26 Oct 2026, 12:06 UTCStructured GitHub Advisory Database record (type=reviewed) from the GitHub REST API.

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.

A Regular Expression Denial of Service vulnerability was discovered in esm before 3.1.0. The issue is that esm's find-indexes is using the unescaped identifiers in a regex, which, in this case, causes an infinite loop.

Dates and revisions

Published by the source: 20 Jun 2019, 14:32 UTC
Last modified by the source: 9 Jan 2023, 05:01 UTC
Source last checked: 26 Oct 2026, 12:06 UTC

Revision 2 · amended · 26 Oct 2026
Amended from ghsa record GHSA-qx4v-6gc5-f2vv
Revision 1 · created · 24 Oct 2026
Published from osv record GHSA-qx4v-6gc5-f2vv

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-qx4v-6gc5-f2vv

Advisory: Regular Expression Denial of Service
IDs: GHSA-qx4v-6gc5-f2vv
Record: https://patchnext.com/advisories/ghsa-qx4v-6gc5-f2vv (revision 2, source checked 26 Oct 2026, 12:06 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: esm 3.1.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm esm: affected < 3.1.0; fixed in 3.1.0

## Suggested inspection (read-only)
- `npm ls esm --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 esm.
- 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-qx4v-6gc5-f2vv (OSV record GHSA-qx4v-6gc5-f2vv lists affected ranges: npm esm >=0 <3.1.0 (fixed))
- Verified: https://github.com/advisories/GHSA-qx4v-6gc5-f2vv (GitHub-reviewed advisory GHSA-qx4v-6gc5-f2vv lists affected ranges: npm esm >=0 <3.1.0)

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