CVE-2026-33190

CoreDNS TSIG authentication bypass vulnerability (CVE-2026-33190) affects versions prior to 1.14.3 on non-plain-DNS transports. The tsig plugin trusts the transport writer’s TsigStatus() instead of verifying TSIG itself, causing unauthenticated remote access over DoT, DoH, DoH3, DoQ, and gRPC. Do...

CoreDNS has TSIG authentication bypass on DoT, DoH, DoH3, DoQ, and gRPC

Summary CoreDNS' tsig plugin can be bypassed on non-plain-DNS transports because it trusts the transport writer's TsigStatus instead of performing verification itself. In the attached PoC, plain DNS/TCP correctly rejects an invalid TSIG NOTAUTH, while the same invalid-TSIG request is accepted ove...