Home assistant is an open source home automation. Whilst auditing the frontend code to identify hidden parameters, Cure53 detected auth_callback=1, which is leveraged by the WebSocket authentication logic in tandem with the state parameter. The state parameter contains the hassUrl, which is subsequently utilized to establish a WebSocket connection. This behavior permits an attacker to create a malicious Home Assistant link with a modified state parameter that forces the frontend to connect to an alternative WebSocket backend. Henceforth, the attacker can spoof any WebSocket responses and trigger cross site scripting (XSS). Since the XSS is executed on the actual Home Assistant frontend domain, it can connect to the real Home Assistant backend, which essentially represents a comprehensive…