PyJWT: Malformed RSA JWK aborts parsing of an entire JWK Set

Exploitation

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

CVSS

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

EPSS

• CVE-2026-102274: 0.55% estimated exploitation activity in the next 30 days; percentile 46.02 (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.

Summary A malformed RSA JWK inside a JWK Set aborts parsing of the entire set instead of being skipped, because RSAAlgorithm.fromjwk can raise a plain ValueError that isn't caught by PyJWKSet's per-key error-skipping logic. Affected component / version - Package: PyJWT (PyPI, ecosystem pip) - Files: jwt/apijwk.py (PyJWK.init, PyJWKSet.init), jwt/algorithms.py (RSAAlgorithm.fromjwk) - Confirmed present in the master branch as of 2026-09-05 (commit 7144e4534c34810f4525dc4578a32addd8212cff, tag 2.13.0). Directly verified identical in tags 2.9.0, 2.10.0, 2.11.0, 2.12.0, 2.12.1, 2.13.0 -- the vulnerable call and the except PyJWTError guard are unchanged across all six releases. Not verified against any release prior to 2.9.0. Details PyJWKSet.init (jwt/apijwk.py:145-152) iterates each key in a JWK Set: PyJWK.init (apijwk.py:82) calls self.Algorithm.fromjwk(self.jwkdata) with no try/except of its own. For an RSA JWK, this dispatches to RSAAlgorithm.fromjwk (jwt/algorithms.py:539-586). When…

Published by the source

29 Sep 2026, 18:23 UTC

Last modified by the source

1 Oct 2026, 17:55 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-w6j9-cwv2-h6wq

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-w6j9-cwv2-h6wq

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-w6j9-cwv2-h6wq

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# Patch Next advisory brief: CVE-2026-102274

Advisory: PyJWT: Malformed RSA JWK aborts parsing of an entire JWK Set
IDs: CVE-2026-102274, GHSA-w6j9-cwv2-h6wq
Record: https://patchnext.com/advisories/cve-2026-102274 (revision 3, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pyjwt 2.14.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pyjwt: affected >= 2.9.0, <= 2.13.0; fixed in 2.14.0

## Suggested inspection (read-only)
- `python -m pip show pyjwt`: prints the installed version. Run with the environment that serves production active.

## 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 pyjwt.
- 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://github.com/advisories/GHSA-w6j9-cwv2-h6wq (GitHub-reviewed advisory GHSA-w6j9-cwv2-h6wq lists affected ranges: PyPI pyjwt >=2.9.0 <=2.13.0)
- Verified: https://osv.dev/vulnerability/GHSA-w6j9-cwv2-h6wq (OSV record GHSA-w6j9-cwv2-h6wq lists affected ranges: PyPI pyjwt >=2.9.0 <2.14.0 (fixed))

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