CVE-2026-101917

PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)

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.

Scores

Weaknesses (CWE)

• CWE-770

Advisories

• GHSA-2gx3-rcp4-g85q — PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)
• PYSEC-2026-4140 — PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)

European references

• ENISA EUVD · EUVD-2026-88478
• GCVE · GCVE-0-2026-101917

CERT-FR advisories

• CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
• CERTFR-2026-AVI-1249 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

• cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:* < 2.14.0

Affected products

References

• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-2gx3-rcp4-g85q
• https://github.com/jpadilla/pyjwt/commit/ba4853a75fb9676362da17f67d0f64bd18afd4e1
• https://github.com/jpadilla/pyjwt/releases/tag/2.14.0

Sources