PyJWT: PyJWKClient follows redirects when fetching JWKS

Exploitation

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

CVSS

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

EPSS

• CVE-2026-102267: 0.16% estimated exploitation activity in the next 30 days; percentile 5.05 (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 PyJWT 2.13.0 PyJWKClient followed HTTP redirects while fetching a JWKS, without validating the redirect destination. A configured trusted endpoint could therefore redirect the client to a different host. Impact When an application uses PyJWKClient with caller-supplied request headers and an attacker can influence the configured endpoint's response, the redirected request could expose those headers and the redirected response could be used as authoritative key material. This could cause JWKS trust poisoning and, in affected mixed-configuration applications, forged JWT acceptance. The issue requires an attacker-influenced redirect from the configured JWKS endpoint; it is not triggered by a token kid alone. Affected versions PyJWT <= 2.13.0. Fix The issue is fixed on master in commit 0a795b8e1f6ef08f634aa7086fc41cc6d5ce3e56. PyJWKClient now disables automatic redirects for JWKS fetches. Regression tests verify that a redirect is rejected without contacting its destination, while…

Published by the source

29 Sep 2026, 23:15 UTC

Last modified by the source

1 Oct 2026, 17:56 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9v7f-9g4p-ffgj

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-9v7f-9g4p-ffgj

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-9v7f-9g4p-ffgj

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# Patch Next advisory brief: CVE-2026-102267

Advisory: PyJWT: PyJWKClient follows redirects when fetching JWKS
IDs: CVE-2026-102267, GHSA-9v7f-9g4p-ffgj
Record: https://patchnext.com/advisories/cve-2026-102267 (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: High (CVSS 7.4)
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 <= 2.13.0; 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-9v7f-9g4p-ffgj (GitHub-reviewed advisory GHSA-9v7f-9g4p-ffgj lists affected ranges: PyPI pyjwt >=0 <=2.13.0)
- Verified: https://osv.dev/vulnerability/GHSA-9v7f-9g4p-ffgj (OSV record GHSA-9v7f-9g4p-ffgj lists affected ranges: PyPI pyjwt >=0 <2.14.0 (fixed))

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