@eslint/plugin-kit is vulnerable to Regular Expression Denial of Service attacks through ConfigCommentParser

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary The ConfigCommentParser#parseJSONLikeConfig API is vulnerable to a Regular Expression Denial of Service (ReDoS) attack in its only argument. Details The regular expression at packages/plugin-kit/src/config-comment-parser.js:158 is vulnerable to a quadratic runtime attack because the grouped expression is not anchored. This can be solved by prepending the regular expression with [^-a-zA-Z0-9/]. PoC Impact This is a Regular Expression Denial of Service attack which may lead to blocking execution and high CPU usage.

Published by the source

18 Jul 2025, 20:39 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:37 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xffm-g5w8-qvg7

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xffm-g5w8-qvg7

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# Patch Next advisory brief: GHSA-xffm-g5w8-qvg7

Advisory: @eslint/plugin-kit is vulnerable to Regular Expression Denial of Service attacks through ConfigCommentParser
IDs: GHSA-xffm-g5w8-qvg7
Record: https://patchnext.com/advisories/ghsa-xffm-g5w8-qvg7 (revision 3, source checked 26 Oct 2026, 12:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @eslint/plugin-kit 0.3.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @eslint/plugin-kit: affected < 0.3.4; fixed in 0.3.4

## Suggested inspection (read-only)
- `npm ls @eslint/plugin-kit --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 @eslint/plugin-kit.
- 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-xffm-g5w8-qvg7 (OSV record GHSA-xffm-g5w8-qvg7 lists affected ranges: npm @eslint/plugin-kit >=0 <0.3.4 (fixed))
- Verified: https://github.com/advisories/GHSA-xffm-g5w8-qvg7 (GitHub-reviewed advisory GHSA-xffm-g5w8-qvg7 lists affected ranges: npm @eslint/plugin-kit >=0 <0.3.4)

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