Centrifugo: Client-forgeable headers emulation lets any client spoof headers forwarded to proxy backends

Centrifugo is an open-source scalable real-time messaging server. Prior to 6.9.0, Centrifugo copies the client-controlled protocol.ConnectRequest.headers map through OnClientConnecting in internal/client/handler.go, ConnectEvent.Headers, and SetEmulatedHeadersToContext. The requestHeaders path in internal/proxy/http.go, the requestMetadata path in internal/proxy/grpc.go, and the Consume path in internal/unigrpc/grpc.go can forward an allowlisted value as a trusted backend header or metadata value. A remote client can spoof a header such as x-trusted-user for connect, refresh, subscribe, publish, RPC, and related proxy calls when the backend relies on that header for authentication or authorization. The unidirectional gRPC transport has no transport-level HTTP header that can override the emulated value. This issue is fixed in version 6.9.0.

Source published

20 Aug 2026 21:01:00 UTC

Source modified

25 Aug 2026 15:23:47 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N