CVE-2025-12852 is a DLL loading vulnerability classified under CWE-427 (Uncontrolled Search Path Element) found in NEC Corporation's RakurakuMusen Start EX software, affecting all versions. This vulnerability arises because the software improperly controls the search path used to load dynamic link libraries (DLLs). An attacker with local access can manipulate environment variables or the directory structure to influence which DLLs are loaded by the application. This can lead to execution of malicious code with the privileges of the user running the software. The CVSS 4.0 score is 8.4 (high), reflecting the vulnerability's potential to compromise confidentiality, integrity, and availability. The attack vector is local (AV:L), with low attack complexity (AC:L), no privileges required (PR:N), but user interaction is necessary (UI:A). The vulnerability does not require network access or authentication, but the attacker must convince the user to perform an action that triggers the DLL loading. Although no known exploits are currently reported in the wild, the nature of DLL hijacking vulnerabilities makes them attractive for lateral movement and privilege escalation in targeted attacks. The software is used primarily in Japan and some international markets, including parts of Europe, especially in industries where NEC products are deployed. The vulnerability is particularly dangerous because it can be exploited without elevated privileges and can lead to arbitrary code execution, potentially compromising sensitive data or disrupting operations.

For European organizations, this vulnerability poses a significant risk, especially those using NEC RakurakuMusen Start EX in operational environments. Successful exploitation can lead to unauthorized code execution, data breaches, and system compromise. The high impact on confidentiality, integrity, and availability means attackers could steal sensitive information, alter data, or disrupt critical services. Given the local attack vector and requirement for user interaction, insider threats or social engineering could facilitate exploitation. Sectors such as manufacturing, telecommunications, and government agencies using NEC products could face operational disruptions and reputational damage. The lack of patches increases exposure time, and the absence of known exploits does not preclude future attacks. Organizations relying on this software should consider the vulnerability a high priority for remediation to prevent potential lateral movement or privilege escalation within their networks.

1. Immediately restrict and harden DLL search paths by configuring the system to use fully qualified paths for DLL loading and avoid relative paths. 2. Implement application whitelisting and code integrity policies to prevent unauthorized DLLs from loading. 3. Educate users about the risks of executing untrusted files or opening suspicious prompts that could trigger DLL loading. 4. Monitor environment variables and system directories for unauthorized changes that could facilitate DLL hijacking. 5. Use endpoint detection and response (EDR) tools to detect anomalous DLL loading behavior. 6. Isolate systems running RakurakuMusen Start EX to limit lateral movement if compromised. 7. Engage with NEC for official patches or updates and apply them promptly once available. 8. Conduct regular audits of software configurations and environment settings to ensure compliance with security best practices. 9. Limit user privileges where possible to reduce the impact of exploitation. 10. Consider deploying application sandboxing or containerization to contain potential malicious DLL execution.