{"schema":"threatline.record/2","record":{"id":"CVE-2026-84445","aliases":["GHSA-2v4p-qf9q-27wj","GO-2026-6443"],"summary":"gRPC-Go xDS servers: Denial of Service (DoS) via crash due to missing `:authority` and `Host` headers","details":"A vulnerability exists in gRPC-Go servers configured with `xds.NewGRPCServer()` where a crafted request missing both `:authority` and `Host` headers can cause a server panic, resulting in a Denial of Service (DoS).\n\nServers built with `xds.NewGRPCServer` install an xDS routing interceptor on every RPC. This interceptor looks up the request’s `:authority` header to pick a virtual host. The HTTP/2 server transport previously accepted requests that had neither `:authority` nor `Host`. When this happened, the xDS routing interceptor attempted to access the first element of an empty slice of authorities, leading to an index out of bounds panic. Since the per-RPC goroutine does not recover from panics, the entire server process would terminate.\n\nThis panic occurs in the interceptor pipeline, meaning the transport credentials handshake (TLS, mTLS, or ALTS) and HTTP/2 connection establishment must complete successfully before the crafted request can reach this logic.\n- Insecure/Standard TLS: If the server permits insecure (plaintext) connections or standard credentials (where client certs are not checked), any unauthenticated remote attacker can trigger the crash.\n- mTLS / ALTS: If strict transport-level authentication is enforced at the network edge or transport layer (e.g., requiring a valid client certificate), the attacker must possess valid transport credentials to initiate the stream and trigger the panic.\n\n### Impact\nAn attacker can cause a complete outage of the gRPC server by sending a request missing both `:authority` and `Host` headers, provided they can successfully establish a transport connection.\n\n### Patches\nThe issue has been addressed in `master` (and backported to `1.84.0`, `1.83.2` and `1.82.2`). The fix updates the HTTP/2 transport layer to reject requests missing both `:authority` and `Host` headers early, maintaining consistency with and other gRPC language implementations.","categories":["Libraries & packages"],"product":"google.golang.org/grpc","vendor":"grpc","ecosystem":"go","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-2v4p-qf9q-27wj","source_modified_at":"2026-09-25T17:42:24Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"go","name":"google.golang.org/grpc"},"range":"< 1.82.2"},{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-2v4p-qf9q-27wj","source_modified_at":"2026-09-25T17:42:24Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"go","name":"google.golang.org/grpc"},"range":">= 1.83.0, < 1.83.2"},{"source":"GitHub Advisory 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