CVE-2025-27396: Siemens Scalance LPE9403 Privilege Escalation

CVE-2025-27396 Overview

CVE-2025-27396 is a privilege escalation vulnerability affecting Siemens SCALANCE LPE9403 (6GK5998-3GS00-2AC2) industrial edge devices running firmware versions prior to V4.0. The device fails to properly restrict the elevation of privileges required to perform certain valid functionality. An authenticated remote attacker with low privileges can abuse this weakness to escalate to a higher privilege level on the device. The flaw is tracked under CWE-273 (Improper Check for Dropped Privileges) and carries a CVSS 4.0 base score of 8.7.

Critical Impact
An authenticated low-privileged remote attacker can escalate privileges on SCALANCE LPE9403 edge devices, compromising confidentiality, integrity, and availability of the industrial endpoint.

Affected Products

Siemens SCALANCE LPE9403 (6GK5998-3GS00-2AC2) — all firmware versions before V4.0
Siemens SCALANCE LPE9403 firmware (all versions < V4.0)
Siemens SCALANCE LPE9403 hardware platform

Discovery Timeline

2025-03-11 - CVE-2025-27396 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-27396

Vulnerability Analysis

The SCALANCE LPE9403 is a Local Processing Engine used to host industrial edge applications at the network edge in Siemens automation environments. The device exposes management functionality that should enforce strict privilege boundaries between user roles. This vulnerability breaks that boundary by failing to verify that an action requested by a lowly-privileged authenticated user is permitted at that privilege level. As a result, functionality designed for higher-privileged roles becomes reachable from a lower-privileged context. The exploit prerequisites are limited to network reachability and valid low-privileged credentials.

Root Cause

The root cause is mapped to CWE-273, Improper Check for Dropped Privileges. The affected firmware does not properly limit the elevation of privileges required to perform certain valid functions. Authorization decisions are not consistently enforced at the function level, allowing low-privileged sessions to invoke privileged operations.

Attack Vector

The attack is conducted over the network against the LPE9403 management interface. An attacker must already possess valid low-privileged credentials on the device. After authenticating, the attacker invokes the affected functionality to gain elevated privileges, which can then be used to alter device configuration, manipulate hosted edge applications, or pivot deeper into the operational technology (OT) network. No user interaction is required, and exploitation complexity is low. No public proof-of-concept code is available for this issue. Refer to the Siemens Security Advisory SSA-075201 for vendor technical detail.

Detection Methods for CVE-2025-27396

Indicators of Compromise

Unexpected privileged actions (configuration changes, application deployment, user creation) performed under accounts that should hold only low-privileged roles on the LPE9403.
Authentication events from low-privileged accounts followed by administrative API calls or shell-equivalent operations on the device.
Anomalous management-plane traffic to the LPE9403 from hosts that do not normally administer industrial edge devices.

Detection Strategies

Audit LPE9403 access logs for low-privileged users invoking management endpoints or functions associated with administrative roles.
Correlate device-side events with network telemetry to identify privilege transitions that did not pass through an administrative login.
Baseline expected behavior per role on SCALANCE devices and alert on deviations, especially configuration writes from non-admin accounts.

Monitoring Recommendations

Forward SCALANCE LPE9403 syslog and audit data to a centralized SIEM or data lake for retention and correlation across OT and IT events.
Monitor north-south traffic to the device management interface and restrict it to a dedicated administrative VLAN or jump host.
Track firmware version inventory continuously and flag any LPE9403 running a version below V4.0.

How to Mitigate CVE-2025-27396

Immediate Actions Required

Update SCALANCE LPE9403 firmware to version V4.0 or later as published in Siemens advisory SSA-075201.
Inventory all SCALANCE LPE9403 devices in the environment and prioritize patching of internet-exposed or shared-access units.
Rotate credentials for all accounts on affected devices after patching, particularly low-privileged service or operator accounts.

Patch Information

Siemens has addressed the issue in SCALANCE LPE9403 firmware V4.0. Apply this update as documented in the Siemens Security Advisory SSA-075201. Follow Siemens' published guidance for staged firmware deployment in industrial environments and validate device functionality post-upgrade.

Workarounds

Restrict network access to the LPE9403 management interface to trusted engineering workstations using firewall rules or ACLs.
Apply Siemens' general operational guidelines for industrial security, including network segmentation per IEC 62443 and placement of OT assets behind dedicated security gateways.
Limit the assignment of authenticated accounts on the device to the minimum required personnel until firmware V4.0 is deployed.

bash

# Example: restrict management access to LPE9403 via upstream firewall ACL
# Allow only the engineering jump host to reach the device management port
iptables -A FORWARD -s 10.10.20.5/32 -d 10.20.30.10/32 -p tcp --dport 443 -j ACCEPT
iptables -A FORWARD -d 10.20.30.10/32 -p tcp --dport 443 -j DROP