Vulnerability · Published Sep 28, 2026 · Assigned by GitHub_M
CVE-2026-101917PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)
Medium 5.3
In plain English
A medium-severity resource allocation without limits in pyjwt from jpadilla. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT get_signing_key_from_jwt is affected because unknown kid misses force refreshes without a negative cache or minimum refresh interval. This occurs when unauthenticated tokens repeatedly use the same unknown kid or varying kid values absent from the cached JWKS. As a result, each cache miss causes PyJWKClient to refresh the JWKS. Consequently, attacker traffic can amplify outbound requests to the configured JWKS endpoint. This issue is fixed in version 2.14.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pyjwt | no fix listed | DEBIAN-CVE-2026-101917 |
| Debian:13 | pyjwt | no fix listed | DEBIAN-CVE-2026-101917 |
| Debian:14 | pyjwt | 2.14.0-1 | DEBIAN-CVE-2026-101917 |
| PyPI | pyjwt | 2.14.0 | PYSEC-2026-4140 |
| PyPI | pyjwt | 2.14.0 | GHSA-2gx3-rcp4-g85q |
| Ubuntu:22.04:LTS | pyjwt | 2.3.0-1ubuntu0.6 | USN-8934-1 |
| Ubuntu:22.04:LTS | pyjwt | 2.3.0-1ubuntu0.6 | UBUNTU-CVE-2026-101917 |
| Ubuntu:24.04:LTS | pyjwt | 2.7.0-1ubuntu0.4 | USN-8934-1 |
| Ubuntu:24.04:LTS | pyjwt | 2.7.0-1ubuntu0.4 | UBUNTU-CVE-2026-101917 |
| Ubuntu:26.04:LTS | pyjwt | 2.10.1-4ubuntu1.3 | UBUNTU-CVE-2026-101917 |
| Ubuntu:26.04:LTS | pyjwt | 2.10.1-4ubuntu1.3 | USN-8934-1 |
| Ubuntu:26.10 | pyjwt | 2.13.0-1ubuntu1.1 | USN-8934-1 |
| Ubuntu:26.10 | pyjwt | 2.13.0-1ubuntu1.1 | UBUNTU-CVE-2026-101917 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-2gx3-rcp4-g85q x_refsource_CONFIRM
- https://github.com/jpadilla/pyjwt/commit/ba4853a75fb9676362da17f67d0f64bd18afd4e1 x_refsource_MISC
- https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 x_refsource_MISC