CVE-2026-46416 Microsoft UFO shared WebSocket handler state causes cross-client response hijacking
An attacker can hijack WebSocket responses intended for other authenticated clients due to shared state in the Microsoft UFO framework.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-46416?
CVE-2026-46416 is a medium-severity vulnerability in microsoft UFO, published on 27 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Microsoft UFO open-source framework for intelligent automation across devices and platforms. In 3.0.1-4-ge2626659, Microsoft UFO creates one shared UFOWebSocketHandler instance and reuses it for multiple authenticated WebSocket connections. The handler stores per-connection protocol objects in mutable instance fields. Each new WebSocket connection overwrites those fields. Later, message handlers send responses through the shared fields instead of through protocol objects bound to the originating connection. As a result, the most recently connected authenticated client can receive protocol responses that belong to another authenticated client.
Which versions are affected by CVE-2026-46416?
How do I fix CVE-2026-46416?
No fix has been published for CVE-2026-46416 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-46416 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46416 exists.