CVE-2026-46416 Overview
CVE-2026-46416 affects Microsoft UFO, an open-source framework for intelligent automation across devices and platforms. In version 3.0.1-4-ge2626659, the framework instantiates a single shared UFOWebSocketHandler and reuses it across multiple authenticated WebSocket connections. The handler stores per-connection protocol objects in mutable instance fields, which each new connection overwrites. Message handlers then transmit responses through the shared fields instead of through protocol objects bound to the originating session. As a result, the most recently connected authenticated client can receive responses intended for another authenticated client. The issue is classified under [CWE-284] Improper Access Control.
Critical Impact
Authenticated WebSocket clients can receive protocol responses belonging to other authenticated clients, breaking session isolation and exposing automation data across user contexts.
Affected Products
- Microsoft UFO open-source automation framework
- UFO build 3.0.1-4-ge2626659
- Deployments exposing the UFOWebSocketHandler to multiple authenticated clients
Discovery Timeline
- 2026-05-27 - CVE-2026-46416 published to NVD
- 2026-05-27 - Last updated in NVD database
Technical Details for CVE-2026-46416
Vulnerability Analysis
The vulnerability stems from a shared-state design defect in the WebSocket handler layer of Microsoft UFO. The framework constructs one UFOWebSocketHandler instance and reuses it as connections arrive. Per-connection protocol state is stored in mutable instance fields on that singleton handler, not in objects scoped to the connection. When a new authenticated client connects, its protocol object overwrites the prior values held in those fields. Subsequent message handlers read from the shared fields when sending responses. The handler therefore routes outbound responses through whichever protocol object was bound most recently, rather than through the protocol object tied to the originating client.
The practical effect is a cross-client response leak. Responses generated for client A can be dispatched to client B if B connected after A. Because UFO drives automation actions across devices and platforms, leaked responses may include automation results, command outputs, or session metadata exchanged over the WebSocket channel.
Root Cause
The root cause is improper access control through unsafe object sharing. A handler designed to be per-connection is instantiated as a shared singleton, and connection-specific state is stored on instance fields rather than within a connection-scoped context. The design violates the isolation expected between concurrent authenticated sessions [CWE-284].
Attack Vector
Exploitation requires network access to the WebSocket endpoint and valid authentication credentials. An authenticated attacker connects to the UFO WebSocket service after a target client has connected. The attacker's protocol object overwrites the shared fields. Responses generated for the earlier client are then delivered to the attacker's session. No user interaction is required on the victim side. The flaw does not enable code execution, but it breaks confidentiality and integrity of responses across authenticated sessions.
No verified public exploit code is available. See the GitHub Security Advisory GHSA-cwwh-p9rv-4pj4 for the maintainer technical description.
Detection Methods for CVE-2026-46416
Indicators of Compromise
- Authenticated WebSocket clients receiving response payloads that reference sessions, request IDs, or automation tasks they did not initiate.
- Concurrent authenticated WebSocket connections to the UFO endpoint where response correlation IDs do not match the originating client.
- Application logs showing protocol responses dispatched to a connection ID that differs from the request's originating connection ID.
Detection Strategies
- Inspect UFO server logs for mismatches between request connection_id and the connection used to send the corresponding response.
- Instrument the UFOWebSocketHandler to log the identity of the protocol object used per outbound message and alert on overwrites during active sessions.
- Correlate concurrent authenticated session activity to identify response delivery to unintended clients.
Monitoring Recommendations
- Track the count of simultaneously active authenticated WebSocket connections and alert when overlap occurs during sensitive automation tasks.
- Audit network captures of the WebSocket channel for evidence of response payloads delivered to unexpected client sockets.
- Forward UFO application logs to a centralized analytics pipeline for cross-session correlation and anomaly review.
How to Mitigate CVE-2026-46416
Immediate Actions Required
- Restrict the UFO WebSocket endpoint to a single authenticated client per server instance until a patched build is deployed.
- Limit network exposure of the UFO service to trusted operators and remove public reachability.
- Review session and automation logs for evidence of cross-client response delivery.
Patch Information
Refer to the Microsoft UFO Security Advisory GHSA-cwwh-p9rv-4pj4 for the fixed version and upgrade guidance. Upgrade from 3.0.1-4-ge2626659 to the maintainer-designated patched release as soon as it is available in your environment.
Workarounds
- Deploy UFO in a single-tenant configuration so only one authenticated client connects to a given handler at a time.
- Place the WebSocket endpoint behind a reverse proxy that enforces per-client process or container isolation.
- Disable multi-client authenticated access to the UFO WebSocket service until the upgrade is applied.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
