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

Summary

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.

Timeline

1. Aug 20, 2026, 9:01 PM UTCCVE published
2. Aug 25, 2026, 3:23 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: total

3. Aug 25, 2026, 3:23 PM UTCRecord last updated

Affected versions

• centrifugal centrifugo

  fixed in 6.9.0

• github.com/centrifugal/centrifugoGo

  All versions

• github.com/centrifugal/centrifugo/v3Go

  All versions

• github.com/centrifugal/centrifugo/v4Go

  All versions

• github.com/centrifugal/centrifugo/v5Go

  All versions

• github.com/centrifugal/centrifugo/v6Go

  fixed in 6.9.0

• github.com/centrifugal/centrifugoGo

  fixed in 6.9.0

References 4