CVE-2025-40567: Siemens SCALANCE Auth Bypass Vulnerability

CVE-2025-40567 Overview

CVE-2025-40567 is an incorrect authorization vulnerability [CWE-863] in the web interface of multiple Siemens RUGGEDCOM RST2428P and SCALANCE XCH/XCM/XRH/XRM industrial network devices. The Load Rollback functionality fails to properly validate user roles. An authenticated remote attacker holding only the low-privilege guest role can invoke rollback operations and revert configuration changes previously applied by privileged administrators. This affects all firmware versions prior to V3.2 across the listed product families. The flaw undermines the integrity of device configuration on operational technology (OT) networks that rely on these switches for deterministic Ethernet traffic.

Critical Impact

A guest-level authenticated attacker can roll back administrator configuration changes on affected Siemens RUGGEDCOM and SCALANCE devices, disrupting network integrity and potentially reintroducing previously remediated insecure states.

Affected Products

• RUGGEDCOM RST2428P (6GK6242-6PA00) — all versions before V3.2
• SCALANCE XCH328, XCM324, XCM328, XCM332 — all versions before V3.2
• SCALANCE XRH334 and XRM334 variants (24 V DC, 230 V AC, 2x230 V AC, FO and SFP+ models) — all versions before V3.2

Discovery Timeline

• 2025-06-10 - CVE-2025-40567 published to the National Vulnerability Database (NVD)
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-40567

Vulnerability Analysis

The vulnerability resides in the web management interface of affected Siemens industrial switches. The Load Rollback feature is designed to revert a device to a previous saved configuration state. This feature should be restricted to administrative roles that own configuration management. The authorization check performed before executing the rollback does not enforce the required privilege level. As a result, users assigned the guest role, which is intended for read-only monitoring, can execute a state-changing operation reserved for privileged users. The impact is limited to integrity of the device configuration; confidentiality and availability are not directly affected.

Root Cause

The root cause is an incorrect authorization check [CWE-863] on the rollback endpoint. The web interface authenticates the session but omits or misapplies the role check that gates configuration-modifying operations. Guest sessions therefore pass the authorization gate and reach the rollback handler.

Attack Vector

Exploitation requires network reachability to the device web interface and valid guest credentials. No user interaction is required. The attacker sends a rollback request through the web interface, causing the device to load a prior configuration and discard changes made by administrators, including hardening measures, ACL updates, VLAN reassignments, or credential rotations. The vulnerability manifests entirely through the authenticated web endpoint. Refer to the Siemens Security Advisory SSA-693776 for protocol-level details.

Detection Methods for CVE-2025-40567

Indicators of Compromise

• Unexpected configuration reversion events in device audit logs, particularly rollback actions initiated by accounts assigned the guest role.
• Web management access logs showing guest sessions issuing POST requests to rollback endpoints.
• Sudden reappearance of previously removed users, VLANs, ACL entries, or firmware settings on affected switches.

Detection Strategies

• Correlate device syslog entries for Load Rollback operations with the initiating user role and alert when the role is not administrative.
• Baseline configuration hashes on each switch and trigger alerts when the running configuration reverts to a prior known state without an approved change ticket.
• Ingest Siemens device syslog into a centralized SIEM and build detections that join authentication events with configuration-change events.

Monitoring Recommendations

• Enable and forward detailed audit logging from all affected RUGGEDCOM and SCALANCE devices to a central log platform.
• Monitor northbound management VLANs for unauthorized HTTP or HTTPS sessions targeting device web interfaces from non-administrative subnets.
• Track the population of guest accounts and alert on any successful authentication from unexpected source addresses.

How to Mitigate CVE-2025-40567

Immediate Actions Required

• Upgrade affected RUGGEDCOM RST2428P and SCALANCE XCH/XCM/XRH/XRM devices to firmware V3.2 or later.
• Audit all local and remote user accounts on affected devices and remove or disable unused guest accounts.
• Restrict access to the device web management interface to a dedicated, isolated management network.

Patch Information

Siemens has released firmware version V3.2 for all affected product families listed in advisory SSA-693776. Apply the update following Siemens' standard firmware upgrade procedure for RUGGEDCOM and SCALANCE devices. Verify device operation and configuration integrity after the upgrade.

Workarounds

• Disable the guest role or reset guest account passwords to strong values where the role cannot be removed entirely.
• Enforce network segmentation and place device management interfaces behind a firewall that limits access to trusted administrative hosts only.
• Apply Siemens' operational guidelines for industrial security, including defense-in-depth practices described in the vendor advisory.

# Configuration example: restrict web management access with an ACL
# (Syntax varies by RUGGEDCOM/SCALANCE CLI; consult device documentation)
configure
  ip access-list management-acl
    permit tcp 10.10.20.0/24 any eq 443
    deny   tcp any any eq 443
  interface vlan mgmt
    ip access-group management-acl in
commit