Regular Expression Denial of Service in Headers

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-2023-24807: 1.31% estimated exploitation activity in the next 30 days; percentile 70.78 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The Headers.set() and Headers.append() methods are vulnerable to Regular Expression Denial of Service (ReDoS) attacks when untrusted values are passed into the functions. This is due to the inefficient regular expression used to normalize the values in the headerValueNormalize() utility function. Patches This vulnerability was patched in v5.19.1. Workarounds There is no workaround. Please update to an unaffected version. References https://hackerone.com/bugs?reportid=1784449 Credits Carter Snook reported this vulnerability.

Published by the source

16 Feb 2023, 20:46 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 16:40 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from vendor_advisory record nodejs-security-wg:core:106

2. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r6ch-mqf9-qc9w

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-r6ch-mqf9-qc9w

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# Patch Next advisory brief: CVE-2023-24807

Advisory: Regular Expression Denial of Service in Headers
IDs: CVE-2023-24807, GHSA-r6ch-mqf9-qc9w
Record: https://patchnext.com/advisories/cve-2023-24807 (revision 3, source checked 26 Oct 2026, 16:40 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 fix available; fixed versions by package: node 19.6.1, 18.14.1, 16.19.1, 14.21.3; undici 5.19.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- runtime node: affected >= 14.0.0, < 14.21.3; >= 16.0.0, < 16.19.1; >= 18.0.0, < 18.14.1; >= 19.0.0, < 19.6.1; fixed in 19.6.1, 18.14.1, 16.19.1, 14.21.3
- npm undici: affected < 5.19.1; fixed in 5.19.1

## Suggested inspection (read-only)
- runtime node: check the installed version with your package manager.
- `npm ls undici --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 node, undici.
- 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-r6ch-mqf9-qc9w (OSV record GHSA-r6ch-mqf9-qc9w lists affected ranges: npm undici >=0 <5.19.1 (fixed))
- Verified: https://github.com/advisories/GHSA-r6ch-mqf9-qc9w (GitHub-reviewed advisory GHSA-r6ch-mqf9-qc9w lists affected ranges: npm undici >=0 <5.19.1)
- Verified: https://nodejs.org/dist/index.json (The nodejs.org release index dates the first patched release for CVE-2023-24807 to 2023-02-16.)
- Verified: https://raw.githubusercontent.com/nodejs/security-wg/main/vuln/core/106.json (Node.js security working group core entry 106 lists CVE-2023-24807 affecting node >=14.0.0 =16.0.0 =18.0.0 =19.0.0 <19.6.1)

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