CVE-2026-55440 MEDIUM

CVE-2026-55440: Microsoft UFO: COMMAND_RESULTS handler creates unowned sessions, allowing authenticated session-squatting denial of service

Vendor Microsoft
Product UFO
Weakness CWE-400
Published July 16, 2026
Last update July 16, 2026

CVSS base score

6.5/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

July 16, 2026 CVE published