What’s Vulnerable › Vulnerabilities

CVE-2026-101917: PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-28 · updated 2026-10-07
• Weakness: CWE-770

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 products

• jpadilla pyjwt: before 2.14.0 — fixed in 2.14.0

How to fix

Upgrade to a fixed version: jpadilla pyjwt 2.14.0. Check the vendor advisory for mitigations.

References

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

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