Centrifugo's dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass

Summary Centrifugo's dynamic JWKS endpoint feature can verify a JWT for one allowed issuer using a public key cached from another allowed issuer. The JWKS cache and singleflight lookup are keyed only by the JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or other trust-domain...