CVE-2025-61871 is a vulnerability in the Windows version of BUFFALO INC.'s NAS Navigator2 software, specifically versions prior to 3.12.0. The vulnerability stems from the software registering a Windows service with an unquoted file path. In Windows, unquoted service paths containing spaces can be exploited by placing malicious executables in specific locations along the path, which the system may execute with elevated privileges. Here, a user with write permissions on the root directory of the system drive (commonly C:\) can place a malicious executable that the service will run with SYSTEM privileges, effectively allowing privilege escalation to full system control. The CVSS 3.0 score is 6.7 (medium severity), reflecting that the attack vector is local (AV:L), requires low attack complexity (AC:L), but requires high privileges (PR:H), no user interaction (UI:N), and impacts confidentiality, integrity, and availability (C:H/I:H/A:H). Although no public exploits are known, the vulnerability is significant because it can be leveraged by insiders or malware that has gained limited access to escalate privileges. The vulnerability is specific to the Windows client of NAS Navigator2, a utility used to manage BUFFALO NAS devices, which are popular in SMB and enterprise environments for network-attached storage management.

For European organizations, this vulnerability could lead to full system compromise on Windows machines running vulnerable versions of NAS Navigator2. Attackers or malicious insiders with write access to the system drive root could escalate privileges to SYSTEM, potentially leading to unauthorized access to sensitive data stored on the NAS or the host system, disruption of services, or deployment of further malware. This risk is particularly relevant in environments where multiple users share workstations or where endpoint security is lax. The impact extends to confidentiality breaches, integrity violations through unauthorized code execution, and availability disruptions if critical services are compromised or disabled. Given the medium severity and the requirement for local high privileges, the threat is more pronounced in organizations with less stringent endpoint controls or where BUFFALO NAS devices are integral to operations.

1. Upgrade NAS Navigator2 to version 3.12.0 or later, where the unquoted service path issue is resolved. 2. Restrict write permissions on the root directory of the system drive (e.g., C:\) to only trusted administrators to prevent unauthorized file placement. 3. Employ application whitelisting and endpoint protection solutions to detect and block unauthorized executable files in critical system paths. 4. Regularly audit Windows services for unquoted paths using tools or scripts to identify and remediate similar issues proactively. 5. Implement strict user privilege management to minimize the number of users with write access to sensitive system locations. 6. Monitor system logs and security events for unusual service behavior or attempts to write to the system drive root. 7. Educate IT staff and users about the risks of privilege escalation vulnerabilities and the importance of applying patches promptly.