jsonwebtoken vulnerable to signature validation bypass due to insecure default algorithm in jwt.verify()

Exploitation

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

CVSS

6.4 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L

EPSS

• CVE-2022-23540: 0.57% estimated exploitation activity in the next 30 days; percentile 47.33 (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.

Overview In versions <=8.5.1 of jsonwebtoken library, lack of algorithm definition and a falsy secret or key in the jwt.verify() function can lead to signature validation bypass due to defaulting to the none algorithm for signature verification. Am I affected? You will be affected if all the following are true in the jwt.verify() function: - a token with no signature is received - no algorithms are specified - a falsy (e.g. null, false, undefined) secret or key is passed How do I fix it? Update to version 9.0.0 which removes the default support for the none algorithm in the jwt.verify() method. Will the fix impact my users? There will be no impact, if you update to version 9.0.0 and you don’t need to allow for the none algorithm. If you need 'none' algorithm, you have to explicitly specify that in jwt.verify() options.

Published by the source

22 Dec 2022, 03:32 UTC

Last modified by the source

13 Feb 2025, 18:33 UTC

Source last checked

26 Oct 2026, 12:36 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qwph-4952-7xr6

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-qwph-4952-7xr6

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# Patch Next advisory brief: CVE-2022-23540

Advisory: jsonwebtoken vulnerable to signature validation bypass due to insecure default algorithm in jwt.verify()
IDs: CVE-2022-23540, GHSA-qwph-4952-7xr6
Record: https://patchnext.com/advisories/cve-2022-23540 (revision 2, source checked 26 Oct 2026, 12:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: jsonwebtoken 9.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm jsonwebtoken: affected < 9.0.0; fixed in 9.0.0

## Suggested inspection (read-only)
- `npm ls jsonwebtoken --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 jsonwebtoken.
- 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-qwph-4952-7xr6 (OSV record GHSA-qwph-4952-7xr6 lists affected ranges: npm jsonwebtoken >=0 <9.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-qwph-4952-7xr6 (GitHub-reviewed advisory GHSA-qwph-4952-7xr6 lists affected ranges: npm jsonwebtoken >=0 <9.0.0)

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