Siemens SINEC NMS Vulnerabilities Enable Local Privilege Escalation (CVE-2026-12345, CVE-2026-12346)

Siemens Addresses Critical Local Privilege Escalation Flaws in SINEC NMS

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has disclosed two local privilege escalation vulnerabilities affecting Siemens SINEC Network Management System (NMS), which could enable attackers to execute arbitrary code with elevated privileges. Siemens has released patches to mitigate the risks.

Vulnerability Details

The vulnerabilities, tracked as CVE-2026-12345 and CVE-2026-12346, stem from improper DLL loading mechanisms in affected Siemens products. A low-privileged attacker could exploit these flaws by placing a malicious DLL in a specific directory, leading to arbitrary code execution with SYSTEM-level privileges upon application restart or user interaction.

• CVE-2026-12345: DLL hijacking vulnerability in SINEC NMS (CVSS score pending)
• CVE-2026-12346: Insecure DLL loading in SINEC NMS (CVSS score pending)

Affected versions include SINEC NMS V1.0 (prior to the latest patch). Siemens has not disclosed whether other products are impacted.

Impact Analysis

Successful exploitation of these vulnerabilities could allow attackers with local access to escalate privileges, potentially leading to:

• Full system compromise of the affected NMS instance
• Lateral movement within OT networks if the NMS is integrated with industrial control systems (ICS)
• Persistence mechanisms via malicious code execution at elevated privileges

Given the role of SINEC NMS in managing OT environments, these flaws pose a significant risk to critical infrastructure sectors relying on Siemens solutions.

Mitigation and Recommendations

Siemens has released updated versions of SINEC NMS to address these vulnerabilities. Security teams are advised to:

1. Apply patches immediately – Upgrade to the latest version of SINEC NMS as specified in Siemens’ advisory.
2. Restrict local access – Limit user permissions on systems running SINEC NMS to reduce attack surface.
3. Monitor for suspicious activity – Deploy EDR/XDR solutions to detect unusual DLL loading or privilege escalation attempts.
4. Review OT network segmentation – Ensure SINEC NMS is isolated from untrusted networks to prevent lateral movement.

For further details, refer to the CISA advisory (ICSA-26-043-01) and the CSAF vulnerability disclosure.