A vulnerability in n8n's Hosted Chat feature allows unauthenticated remote attackers to hijack chat executions via the /chat WebSocket endpoint. Attackers who identify a valid execution ID for a workflow in a waiting state can intercept prompts and submit arbitrary input to influence workflow behavior. This affects instances with public Hosted Chat workflows configured with no authentication. The issue is fixed in versions 1.123.32, 2.17.4, and 2.18.1. Temporary mitigation includes enabling authentication on Chat Trigger nodes.