CVE-2025-66271 is a local privilege escalation vulnerability affecting ELECOM CO.,LTD.'s Clone for Windows software versions prior to 2.36. The root cause is the registration of a Windows service with an unquoted file path. In Windows, if a service executable path contains spaces and is not enclosed in quotes, the system may interpret the path incorrectly and search for executables in unintended directories. This allows an attacker with write access to the root directory of the system drive (e.g., C:\) to place a malicious executable that the service will run with SYSTEM privileges during startup or service restart. The vulnerability requires the attacker to have local write permissions on the root of the system drive, which is a high privilege but can be obtained through other means such as misconfigured permissions or other vulnerabilities. Exploiting this flaw can lead to full system compromise, allowing arbitrary code execution with the highest Windows privileges, impacting confidentiality, integrity, and availability of the system. The CVSS 3.0 score of 6.7 reflects the medium severity due to the requirement of local privileges and no user interaction. No public exploits are known yet, but the vulnerability is publicly disclosed and should be addressed promptly. The vulnerability is specific to Clone for Windows software, so the impact is limited to environments where this product is deployed.

For European organizations, this vulnerability poses a significant risk where Clone for Windows is deployed, especially in environments where local users have write access to the system drive root. Successful exploitation can lead to full SYSTEM-level compromise, enabling attackers to manipulate sensitive data, disrupt services, or move laterally within networks. Critical infrastructure, government agencies, and enterprises relying on this software for backup or cloning operations could face operational disruptions and data breaches. The medium CVSS score indicates moderate ease of exploitation but high impact, meaning organizations with less strict local permission controls are particularly vulnerable. Since no known exploits are in the wild, the immediate risk is moderate but could escalate if exploit code is developed. European entities with stringent compliance requirements (e.g., GDPR) must consider the confidentiality and integrity risks posed by this vulnerability.

Organizations should immediately upgrade Clone for Windows to version 2.36 or later where the vulnerability is fixed. Until patching is possible, restrict write permissions on the root directory of the system drive to only trusted administrators to prevent unauthorized code placement. Conduct audits of local permissions to ensure no untrusted users have write access to critical system directories. Employ application whitelisting and endpoint protection solutions to detect and block unauthorized service modifications or suspicious executables in system paths. Regularly monitor Windows service configurations for unquoted paths and correct them manually if necessary. Implement least privilege principles to limit local user permissions and reduce the attack surface. Additionally, educate system administrators about this vulnerability and the risks of unquoted service paths to prevent similar issues in other software.