The JWT signing key cache in TokenKeyResolver uses kid as the sole cache key without namespacing by authority. In applications with multiple JwtBearer schemes pointing to different identity providers, a key fetched for one scheme can satisfy token validation for another. Additionally, cached keys have no expiration, so rotated or revoked keys remain trusted until the application process restarts.
// impact
In multi-scheme deployments, an attacker who controls one identity provider's signing key can forge tokens accepted by other schemes within the same application. For all applications using TokenKeyResolver, a signing key removed from the identity provider's JWKS endpoint remains trusted indefinitely.
// mitigations
If an immediate upgrade is not possible:
In multi-scheme deployments, configure only one JwtBearer scheme per application when different identity providers are required.
Restart the application process after an identity provider signing key rotation to clear stale cached keys.
// cvss v3.1 vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Checked 2026-09-26 at 01:00 UTC. The most recent advisory here was published 2026-07-02. Updated continuously from NVD, GHSA, OSV and CNA feeds.