CVE-2026-33190 CoreDNS TSIG authentication bypass on encrypted DNS transports

CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the tsig plugin can be bypassed on non-plain-DNS transports DoT, DoH, DoH3, DoQ, and gRPC because it trusts the transport writer's TsigStatus instead of performing verification itself. The DoH and DoH3 writer's TsigStatus...

CoreDNS has TSIG authentication bypass on gRPC and QUIC transports

Summary The gRPC, QUIC, DoH, and DoH3 transports in CoreDNS incorrectly handle TSIG authentication. For gRPC and QUIC, CoreDNS checks whether the TSIG key name exists in the config, but does not actually verify the TSIG HMAC. If the key name matches, tsigStatus remains nil and the tsig plugin...