CVE-2025-66264 is a vulnerability categorized under CWE-428 (Unquoted Search Path or Element) affecting MegaTec Taiwan's ClientMate software, specifically version 6.2.2. The issue arises because the CMService.exe service, which runs with SYSTEM privileges, is configured with an unquoted service path. In Windows environments, when a service path contains spaces and is not enclosed in quotes, the system may incorrectly interpret the path and search for executables in unintended directories. A local attacker who has write privileges to any directory in the unquoted path can place a malicious executable that the system will execute with elevated SYSTEM privileges during service startup. This leads to privilege escalation from a lower-privileged user to SYSTEM, potentially allowing full control over the affected system. The vulnerability requires local access and some privileges (PR:L) but does not require user interaction (UI:N). The CVSS 4.0 base score is 7.2, reflecting high severity due to the potential impact on confidentiality, integrity, and availability, and the complexity being low. No patches or exploits are currently publicly available, but the vulnerability is published and should be addressed promptly. The vulnerability is particularly dangerous because services running as SYSTEM have unrestricted access to the system, and exploitation could lead to persistent control or lateral movement within a network.

For European organizations, this vulnerability poses a significant risk especially in environments where ClientMate 6.2.2 is deployed on endpoints or servers. Successful exploitation allows attackers to escalate privileges locally to SYSTEM, enabling them to bypass security controls, install persistent malware, exfiltrate sensitive data, or disrupt operations. This is particularly concerning for critical infrastructure, financial institutions, healthcare providers, and government agencies that rely on MegaTec software for client management or endpoint services. The vulnerability could facilitate insider threats or attacks leveraging compromised user accounts with limited privileges. Given the SYSTEM-level access gained, attackers could also disable security tools, modify logs, or move laterally across networks, increasing the overall impact. The lack of known exploits in the wild currently reduces immediate risk, but the presence of the vulnerability in a widely used service means that targeted attacks or automated exploitation could emerge, especially in high-value European sectors.

Organizations should immediately audit their systems to identify installations of MegaTec ClientMate version 6.2.2. Since no official patch is currently available, administrators should manually verify and correct the service path for CMService.exe by enclosing the path in quotes to prevent unquoted path exploitation. Additionally, restrict write permissions on all directories in the service path to trusted administrators only, preventing unauthorized users from placing malicious executables. Employ application whitelisting to block unauthorized executables from running, and monitor system logs for unusual service start events or unexpected executable launches. Implement endpoint detection and response (EDR) solutions to detect privilege escalation attempts. Regularly review local user privileges and remove unnecessary write permissions. Once a vendor patch is released, prioritize deployment. Finally, educate local administrators and users about the risks of local privilege escalation and the importance of maintaining strict filesystem permissions.