CVE-2025-40568: Siemens SCALANCE Auth Bypass Vulnerability

CVE-2025-40568 Overview

CVE-2025-40568 is an incorrect authorization vulnerability [CWE-863] in the web interface of multiple Siemens RUGGEDCOM and SCALANCE industrial network devices. The flaw resides in an internal session termination function that fails to properly validate the caller's role. An authenticated remote attacker holding only the low-privilege guest role can terminate sessions belonging to legitimate users. The issue affects all firmware versions prior to V3.2 across the RUGGEDCOM RST2428P and a large family of SCALANCE XCH, XCM, XRH, and XRM switches used in operational technology (OT) networks.

Critical Impact
A guest-level authenticated attacker can disrupt administrative and operator sessions on managed industrial switches, degrading availability of network management for OT environments.

Affected Products

RUGGEDCOM RST2428P (6GK6242-6PA00) — all versions before V3.2
SCALANCE XCH328, XCM324, XCM328, XCM332 series switches — all versions before V3.2
SCALANCE XRH334 and XRM334 series switches (multiple hardware variants) — all versions before V3.2

Discovery Timeline

2025-06-10 - CVE-2025-40568 published to NVD alongside Siemens advisory SSA-693776
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-40568

Vulnerability Analysis

The affected devices expose a web management interface that supports multiple user roles, including a low-privileged guest role. Internally, the interface provides functionality to terminate active sessions, typically intended for administrators. The session termination endpoint does not verify whether the calling account holds sufficient privileges to act on other users' sessions. As a result, a guest account can invoke the function against sessions belonging to administrators or operators. The impact is limited to availability of the management plane; confidentiality and integrity of switch configuration and forwarded traffic are not affected. In OT environments, forced logouts can interrupt configuration changes, incident response actions, and monitoring workflows.

Root Cause

The root cause is a missing authorization check on the session termination handler in the web interface. The handler authenticates the request but does not enforce a role-based access control decision before performing the destructive action. This maps directly to CWE-863: Incorrect Authorization, where an access control mechanism is present but incorrectly applied.

Attack Vector

Exploitation requires network reachability to the device's web management interface and valid credentials for any account, including the built-in guest role. The attacker sends a crafted request to the internal session termination endpoint referencing an active session identifier belonging to another user. The device processes the request and tears down the targeted session without evaluating the caller's role. No user interaction from the victim is required. See the Siemens Security Advisory SSA-693776 for vendor-provided technical details.

Detection Methods for CVE-2025-40568

Indicators of Compromise

Unexpected session termination events for administrator or operator accounts in device audit logs.
Web management sessions from guest accounts issuing requests to session management endpoints.
Repeated logout events for privileged users originating from within short time windows.

Detection Strategies

Forward RUGGEDCOM and SCALANCE syslog and audit records to a centralized SIEM and alert on session termination actions initiated by non-administrative roles.
Correlate guest role authentication events with subsequent session-management HTTP requests to the device web interface.
Baseline normal administrative session durations and flag abnormal, involuntary session closures.

Monitoring Recommendations

Enable verbose web interface auditing on affected devices where supported.
Monitor management VLAN traffic for HTTP/HTTPS requests to session endpoints from unexpected sources.
Track authentication activity for the built-in guest account and disable it where not required.

How to Mitigate CVE-2025-40568

Immediate Actions Required

Upgrade affected RUGGEDCOM and SCALANCE devices to firmware V3.2 or later.
Disable the guest role or remove unused guest accounts on the device web interface.
Restrict management interface access to a dedicated, segmented management network.

Patch Information

Siemens has released firmware V3.2 for the affected RUGGEDCOM RST2428P and SCALANCE XCH, XCM, XRH, and XRM product families. Refer to the Siemens Security Advisory SSA-693776 for the specific fixed versions per product identifier and download instructions through the Siemens Industry Online Support portal.

Workarounds

Enforce strong role assignment policies and avoid provisioning guest accounts on production switches.
Place device management interfaces behind firewalls that permit access only from trusted engineering workstations.
Apply Siemens' operational guidelines for securing industrial devices, including defense-in-depth network segmentation.

bash

# Configuration example: restrict management access with an ACL (illustrative)
# Only permit the engineering workstation subnet to reach the device web UI
configure terminal
ip access-list extended MGMT-WEB
  permit tcp 10.10.20.0 0.0.0.255 host <device-mgmt-ip> eq 443
  deny   tcp any host <device-mgmt-ip> eq 443
  permit ip any any
end