CVE-2025-27394 Overview
CVE-2025-27394 is a command injection vulnerability affecting Siemens SCALANCE LPE9403 (6GK5998-3GS00-2AC2) devices running firmware versions prior to V4.0. The flaw exists in the SNMP user creation functionality, where the device fails to sanitize user-supplied input. An authenticated attacker with high privileges can inject operating system commands and execute arbitrary code on the device. The weakness is classified under [CWE-78] (Improper Neutralization of Special Elements used in an OS Command). Siemens published advisory SSA-075201 describing the issue and providing remediation guidance.
Critical Impact
Successful exploitation grants arbitrary code execution on SCALANCE LPE9403 edge devices, compromising confidentiality, integrity, and availability of industrial network infrastructure.
Affected Products
- Siemens SCALANCE LPE9403 (6GK5998-3GS00-2AC2) — all firmware versions before V4.0
- Siemens SCALANCE LPE9403 firmware
- Siemens SCALANCE LPE9403 hardware platform
Discovery Timeline
- 2025-03-11 - CVE-2025-27394 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-27394
Vulnerability Analysis
The SCALANCE LPE9403 is a Linux Processing Engine used at the edge of industrial networks for hosting applications and bridging operational technology environments. The vulnerability resides in the workflow that handles creation of new Simple Network Management Protocol (SNMP) users. Input fields supplied during user creation are passed to underlying system calls without proper neutralization of shell metacharacters. An attacker who already holds high-privilege administrative credentials can submit crafted values that break out of the intended command context. The injected payload then executes with the privileges of the SNMP management process on the device.
Root Cause
The root cause is improper neutralization of special elements used in an OS command [CWE-78]. The SNMP user management routine concatenates attacker-controlled strings into a shell command without escaping or argument-array invocation, enabling command injection.
Attack Vector
Exploitation requires network access to the device management interface and authenticated administrative credentials. No user interaction is required. Once authenticated, the attacker invokes the SNMP user creation operation with malicious metacharacters embedded in a user parameter, achieving arbitrary code execution on the underlying Linux platform.
No public proof-of-concept code is available for this issue. Refer to the Siemens Security Advisory SSA-075201 for vendor technical details.
Detection Methods for CVE-2025-27394
Indicators of Compromise
- Unexpected SNMP user creation events in device audit logs, especially with unusual characters such as ;, |, `, $(), or newline sequences in the username field.
- New or unknown processes spawned by the SNMP daemon on the LPE9403 outside of normal management activity.
- Outbound network connections initiated by the device to unfamiliar hosts following administrative login sessions.
Detection Strategies
- Monitor the device management interface for administrative API or web calls that create SNMP users with payloads containing shell metacharacters.
- Correlate authentication events for privileged accounts with subsequent SNMP configuration changes to identify abuse of legitimate credentials.
- Baseline normal LPE9403 process and network behavior, then alert on deviations such as new listening sockets or reverse shell patterns.
Monitoring Recommendations
- Forward LPE9403 syslog and audit data to a centralized SIEM for retention and correlation across the OT environment.
- Track all access to the device administrative interface and require alerting on configuration changes performed outside approved change windows.
- Alert on any firmware integrity or service restart events that occur without an associated authorized maintenance ticket.
How to Mitigate CVE-2025-27394
Immediate Actions Required
- Update SCALANCE LPE9403 firmware to V4.0 or later as directed by Siemens advisory SSA-075201.
- Restrict management network access to the LPE9403 using firewall rules and dedicated administrative VLANs.
- Rotate credentials for any administrative accounts on the device and audit recent SNMP user creation activity.
- Apply the principle of least privilege so that only required personnel hold high-privilege roles on the device.
Patch Information
Siemens addressed the issue in SCALANCE LPE9403 firmware V4.0. Operators should download the fixed firmware package from Siemens Industry Online Support and follow the upgrade procedure documented in the Siemens Security Advisory SSA-075201. Verify firmware integrity after installation and confirm that the SNMP service operates as expected.
Workarounds
- If immediate patching is not possible, disable SNMP user management functions and avoid creating new SNMP users until the firmware is updated.
- Place the device behind a strictly controlled jump host and limit management plane reachability to known administrative workstations.
- Apply Siemens operational guidelines for securing industrial devices, including network segmentation and defense-in-depth controls described in the advisory.
# Example: restrict access to the LPE9403 management interface using iptables on an upstream gateway
iptables -A FORWARD -p tcp -s 10.10.20.0/24 -d 192.0.2.10 --dport 443 -j ACCEPT
iptables -A FORWARD -p udp -s 10.10.20.0/24 -d 192.0.2.10 --dport 161 -j ACCEPT
iptables -A FORWARD -d 192.0.2.10 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
