n8n: Hijacking of Unauthenticated Chat Execution

n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, the /chat WebSocket endpoint used by the Chat Trigger node's Hosted Chat feature did not verify that an incoming connection was authorized to interact with the target execution. An unauthenticated remote attacker who could identify a valid execution ID for a workflow in a waiting state could attach to that execution, receive the pending prompt intended for the legitimate user, and submit arbitrary input to resume or influence downstream workflow behavior. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.