CVE-2026-25655 is a vulnerability classified under CWE-427 (Uncontrolled Search Path Element) affecting Siemens SINEC NMS software versions earlier than V4.0 SP2. The vulnerability arises because the application permits a low-privileged user to improperly modify a configuration file that controls the search path for dynamic link libraries (DLLs). By exploiting this, an attacker can insert or redirect the loading process to malicious DLLs, resulting in arbitrary code execution with administrative privileges on the affected system. The vulnerability requires local access with low privileges but does not require user interaction, making it easier to exploit once access is obtained. The CVSS v3.1 score of 7.8 reflects high severity due to the potential for full system compromise impacting confidentiality, integrity, and availability. Siemens SINEC NMS is a network management system used primarily in industrial and critical infrastructure environments, which increases the risk profile of this vulnerability. No public exploits have been reported yet, but the nature of the flaw suggests that exploitation could lead to significant operational disruption and unauthorized control over network management functions. The vulnerability was reserved and published in early February 2026, and Siemens has released version 4.0 SP2 as a fixed version, although no direct patch links are provided in the data.

For European organizations, especially those in critical infrastructure sectors such as energy, manufacturing, and transportation that rely on Siemens SINEC NMS for network management, this vulnerability poses a significant risk. Exploitation could allow attackers to gain administrative control over network management systems, potentially leading to unauthorized changes in network configurations, disruption of network operations, or further lateral movement within industrial control systems. This could result in data breaches, operational downtime, and safety risks. Given the high integration of Siemens products in European industrial environments, the impact could be widespread, affecting both private and public sector entities. The vulnerability's ability to escalate privileges from low-privileged users to administrative levels exacerbates the threat, especially in environments where local user access is not tightly controlled. The absence of known exploits in the wild provides a window for proactive mitigation, but the risk remains high due to the critical nature of the affected systems.

1. Immediate upgrade to Siemens SINEC NMS version 4.0 SP2 or later, which addresses this vulnerability. 2. Restrict local user access to systems running SINEC NMS to trusted personnel only, minimizing the risk of low-privileged user exploitation. 3. Implement application whitelisting and DLL integrity verification mechanisms to detect and prevent unauthorized DLL loading. 4. Employ strict file system permissions on configuration files to prevent unauthorized modifications by low-privileged users. 5. Monitor system logs and network management activity for unusual DLL loading or configuration changes indicative of exploitation attempts. 6. Conduct regular audits of user privileges and access controls on critical network management systems. 7. Use endpoint detection and response (EDR) tools capable of detecting anomalous DLL injection or code execution behaviors. 8. Develop and test incident response plans specifically for network management system compromises to ensure rapid containment and recovery.