Siemens SINEC NMS Local Privilege Escalation Vulnerability (CVE-2026-25656) Patched
A local privilege escalation vulnerability in Siemens SINEC NMS allows attackers with low-privileged attackers to gain SYSTEM access via an unsecured OpenSSL configuration file.
Siemens has released a security update to address a local privilege escalation vulnerability in its SINEC Network Management System (NMS), tracked as CVE-2026-25656. The flaw, reported by Michael DePlante of Trend Micro's Zero Day Initiative, carries a CVSS score of 7.8 and allows attackers with low-privileged code execution to escalate privileges to SYSTEM.
The vulnerability stems from an uncontrolled search path element in the product's OpenSSL configuration. Specifically, SINEC NMS loads an OpenSSL configuration file from an unsecured location, which an attacker can manipulate to inject malicious code. By exploiting this weakness, a local attacker who has already gained limited code execution on the target system can escalate their privileges to the highest level—SYSTEM—and execute arbitrary code.
Siemens has issued an update to correct the vulnerability, as detailed in its security advisory (SSA-311973). The advisory is available on the Siemens ProductCERT portal. The disclosure timeline shows the vulnerability was reported to Siemens on September 19, 2025, and the coordinated public release of the coordinated public advisory occurred on February 25, 2026.
SINEC NMS is a network management platform used in industrial environments to monitor and manage Siemens industrial networking devices. The privilege escalation risk is particularly concerning in operational technology (OT) environments, where network management systems often have broad access to critical infrastructure. An attacker who gains SYSTEM-level access could potentially pivot to other devices, disrupt operations, or exfiltrate sensitive data.
While the vulnerability requires local access, it is a reminder of the importance of securing configuration files and search paths in industrial software. Siemens has not reported active exploitation in the wild, but the availability of a public advisory and the involvement of a well-known researcher increase the likelihood of proof-of-concept code emerging.
Organizations using SINEC NMS should apply the update as soon as possible. As a mitigation, administrators should also restrict local access to the system and monitor for unusual process behavior. This vulnerability adds to a growing list of privilege escalation flaws in industrial control system (ICS) software, underscoring the need for rigorous patch management in OT environments.