CVE-2026-55440
Received Received - Intake

Microsoft UFO Framework Session Hijacking Vulnerability

Publication date: 2026-07-16

Last updated on: 2026-07-16

Assigner: GitHub, Inc.

Description
Microsoft UFO open-source framework for intelligent automation across devices and platforms. Prior to 3.0.7, the COMMAND_RESULTS handler in ufo/server/ws/handler.py called get_or_create_session in ufo/server/services/session_manager.py without owner_client_id, allowing an authenticated client to create an unowned attacker-chosen session_id such as constellation_task_id = f"{task_name}@{task_id}" and deny the legitimate owner or exhaust memory with phantom sessions. This issue is fixed in version 3.0.7.

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Meta Information

Published
2026-07-16
Last Modified
2026-07-16
Generated
2026-07-16
AI Q&A
2026-07-16
EPSS Evaluated
N/A
NVD
CVE-2026-55440
EUVD
EUVD-2026-44947

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
microsoft ufo to 3.0.7 (exc)
microsoft ufo 3.0.7

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

CVE-2026-55440 is a session-squatting vulnerability in Microsoft's UFO open-source framework. It allows an authenticated attacker to create unowned sessions with attacker-chosen IDs by exploiting the COMMAND_RESULTS handler in the WebSocket server. This can deny legitimate users access to their sessions or exhaust server memory by creating phantom sessions.

Detection Guidance

To detect this vulnerability, monitor for unauthorized session creation in the UFO WebSocket server logs. Look for COMMAND_RESULTS messages with session IDs not tied to any legitimate task execution. Check for repeated session ID patterns like 'constellation_task_id@task_id' without corresponding TASK messages. Inspect memory usage for unexplained spikes, which may indicate phantom session creation.

Impact Analysis

This vulnerability can impact you by allowing attackers to block your access to legitimate sessions, preventing you from executing tasks or retrieving results. It may also cause system instability or crashes due to memory exhaustion from phantom sessions.

Mitigation Strategies

Upgrade to UFO version 3.0.7 or later immediately. Ensure all session creation paths enforce ownership checks by binding COMMAND_RESULTS to the connection's registered identity. Monitor and restrict WebSocket server access to authenticated clients only. Review and remove any unowned sessions periodically to prevent resource exhaustion.

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