CVE-2025-10089 is an Uncontrolled Search Path Element vulnerability (CWE-427) affecting all versions of Mitsubishi Electric Corporation's MILCO.S Setting Application and its variants, including MILCO.S Setting Application (IR), MILCO.S Easy Setting Application (IR), and MILCO.S Easy Switch Application (IR). The vulnerability allows a local attacker to execute arbitrary code by exploiting the way the installer loads DLLs during the installation process. Specifically, the installer does not securely specify the DLL search path, allowing an attacker to place a malicious DLL in a location that the installer searches before the legitimate DLL, resulting in the malicious code being loaded and executed with the installer's privileges. This flaw only manifests during installation and does not affect the application once installed. The vulnerability is mitigated if the installer executable is digitally signed by "Mitsubishi Electric Lighting," as verified via the Digital Signatures tab on the executable's properties. Users who download the installer directly from Mitsubishi Electric's official website are not at risk of malicious code injection, as the official installer is signed and trusted. The CVSS v3.1 base score is 7.7 (High), reflecting local attack vector (AV:L), high attack complexity (AC:H), no privileges required (PR:N), required user interaction (UI:R), scope change (S:C), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No known exploits are currently reported in the wild. The vulnerability underscores the importance of secure DLL loading practices and verifying digital signatures to prevent code execution attacks during software installation.

For European organizations, this vulnerability poses a significant risk primarily during the installation phase of the MILCO.S Setting Application and its variants. Successful exploitation can lead to arbitrary code execution with the privileges of the installer process, potentially allowing attackers to install persistent malware, escalate privileges, or disrupt lighting control systems. Given that lighting control systems may be integrated into critical infrastructure, manufacturing facilities, commercial buildings, and smart building environments, compromise could lead to operational disruptions, safety hazards, and data breaches. The requirement for local access and user interaction limits remote exploitation but increases risk from insider threats or social engineering attacks targeting installation personnel. The high impact on confidentiality, integrity, and availability means that attackers could manipulate system behavior, steal sensitive configuration data, or cause denial of service. European organizations relying on Mitsubishi Electric's lighting control solutions should be aware of this risk, especially in sectors where lighting systems are part of broader industrial control or building management systems.

1. Verify the digital signature of the installer executable before running it; ensure the signer name is "Mitsubishi Electric Lighting" to confirm authenticity and that the vulnerability is patched. 2. Obtain installers only from the official Mitsubishi Electric website or trusted sources to avoid tampered installers. 3. Restrict installation privileges to trusted IT or facilities personnel to reduce the risk of malicious DLL placement by unauthorized users. 4. Implement application whitelisting and endpoint protection solutions that monitor and block unauthorized DLLs from loading during installation processes. 5. Educate staff responsible for installation about the risks of running unsigned or unverified installers and the importance of verifying digital signatures. 6. Consider performing installations in isolated or controlled environments to limit the impact of potential exploitation. 7. Monitor system logs and file system changes during installation for signs of suspicious activity. 8. Engage with Mitsubishi Electric for updates or patches that explicitly address this vulnerability and apply them promptly once available.