Executive brief
Microsoft UFO is an open-source framework used for automating tasks across different devices and platforms. A security flaw in its communication system allows a user to accidentally receive data or command confirmations intended for a different user. This could lead to the exposure of sensitive system information or the hijacking of automation sessions between different connected clients.
Technical details
The vulnerability exists in the UFOWebSocketHandler within 'ufo/server/app.py' and 'ufo/server/ws/handler.py'. The framework initializes a single shared handler instance for all '/ws' connections and stores per-connection protocol objects (such as transport, heartbeat, and task protocols) in mutable instance fields. When a new client connects, it overwrites these shared fields with its own connection state. Subsequent message handlers then use these shared fields to route responses, causing the server to send data (such as device_info_response or task acknowledgments) to the most recently connected client rather than the client that originated the request. This results in an authenticated cross-client WebSocket response hijack.
Affected products
- Microsoft UFO 3.0.1-4-ge2626659
Timeline
- 2026-05-14: advisory: GitHub Security Advisory published
- 2026-05-27: disclosed: CVE published to NVD