CVE-2025-40735: Siemens Sinec NMS SQLi Vulnerability

CVE-2025-40735 Overview

CVE-2025-40735 is a SQL injection vulnerability affecting Siemens SINEC Network Management System (NMS) in all versions prior to V4.0. The flaw allows an unauthenticated remote attacker to execute arbitrary SQL queries against the backend database. Successful exploitation can compromise the confidentiality, integrity, and availability of data managed by the NMS platform. The weakness is classified under CWE-89: Improper Neutralization of Special Elements used in an SQL Command.

SINEC NMS is deployed in industrial environments to manage and monitor Siemens network infrastructure. A successful attack against this management plane can disrupt operational technology (OT) visibility and control.

Critical Impact
An unauthenticated remote attacker reachable on the network can execute arbitrary SQL on the SINEC NMS database, exposing or modifying sensitive industrial network management data.

Affected Products

Siemens SINEC NMS — all versions prior to V4.0
Component: siemens:sinec_nms
Deployments exposing the SINEC NMS web interface to reachable networks

Discovery Timeline

2025-07-08 - CVE-2025-40735 published to the National Vulnerability Database (NVD)
2025-08-21 - Last updated in NVD database

Technical Details for CVE-2025-40735

Vulnerability Analysis

The vulnerability stems from improper neutralization of user-supplied input incorporated into SQL statements executed by SINEC NMS. An attacker submits crafted parameters to an exposed endpoint, and the server concatenates that input directly into a SQL query. The database engine then executes attacker-controlled SQL alongside the intended query.

Because the issue is reachable without authentication, the attack surface includes any network position with access to the management interface. The CWE-89 classification confirms the root cause as missing or insufficient input sanitization at the data access layer.

The affected component is the SINEC NMS server-side application that handles HTTP requests and translates them into database operations. SINEC NMS sits at the management plane of Siemens industrial networks, so the database contains topology, device inventory, credentials, and configuration data that are valuable to attackers targeting OT environments.

Root Cause

The SINEC NMS application fails to neutralize special SQL characters and metacharacters in at least one request parameter before incorporating it into a SQL statement. Parameterized queries or prepared statements were not consistently applied across the affected code paths.

Attack Vector

An unauthenticated attacker sends a crafted HTTP request containing SQL syntax in a vulnerable parameter to the SINEC NMS server. The server executes the injected SQL, allowing the attacker to read arbitrary tables, modify records, or in some database configurations escalate to command execution through database-resident features. Refer to the Siemens Security Advisory SSA-078892 for vendor technical details.

Detection Methods for CVE-2025-40735

Indicators of Compromise

Unexpected HTTP requests to SINEC NMS endpoints containing SQL metacharacters such as ', --, ;, UNION, or SELECT in parameter values
Database error messages or anomalously large response bodies returned from SINEC NMS application logs
New, modified, or unexpected rows in SINEC NMS database tables outside of normal administrative activity
Outbound connections initiated by the SINEC NMS host to unfamiliar destinations following suspicious HTTP traffic

Detection Strategies

Inspect web server and application logs on SINEC NMS hosts for parameter values containing SQL syntax, encoded payloads, or boolean-based injection patterns
Deploy a web application firewall (WAF) or network IDS signature set tuned for SQL injection patterns directed at the SINEC NMS management interface
Correlate authentication telemetry with database query telemetry to identify SQL activity that does not map to an authenticated session

Monitoring Recommendations

Forward SINEC NMS application, web server, and database audit logs to a centralized SIEM for retention and correlation
Alert on database queries originating from the SINEC NMS service account that deviate from established query baselines
Monitor network segments where SINEC NMS is reachable for unauthenticated scanning or fuzzing activity targeting management endpoints

How to Mitigate CVE-2025-40735

Immediate Actions Required

Upgrade SINEC NMS to V4.0 or later as directed in Siemens Security Advisory SSA-078892
Restrict network access to the SINEC NMS management interface to trusted administrative networks only
Review SINEC NMS database and application logs for evidence of prior exploitation
Rotate credentials stored in or accessible through SINEC NMS if compromise is suspected

Patch Information

Siemens has released SINEC NMS V4.0 to address CVE-2025-40735. All versions prior to V4.0 remain vulnerable. The vendor advisory at Siemens ProductCERT SSA-078892 contains the authoritative remediation guidance and fixed version details.

Workarounds

Place SINEC NMS behind a firewall and limit inbound access to a defined set of administrative source addresses
Segment SINEC NMS from general IT and OT production networks following ISA/IEC 62443 zone and conduit guidance referenced by Siemens
Deploy a reverse proxy or WAF that filters SQL injection patterns in front of the SINEC NMS web interface until patching is complete
Disable or restrict any unused SINEC NMS endpoints and interfaces to reduce exposed attack surface

bash

# Example: restrict SINEC NMS web access to an administrative subnet using iptables
# Replace 10.10.20.0/24 with your administrative network and eth0 with the correct interface
iptables -A INPUT -i eth0 -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 443 -j DROP