CVE-2024-39868: Siemens Sinema Auth Bypass Vulnerability

CVE-2024-39868 Overview

CVE-2024-39868 affects Siemens SINEMA Remote Connect Server versions prior to V3.2 SP1. The vulnerability stems from improper authentication validation in the web interface. An unauthenticated attacker on the network can access and modify Virtual Extensible LAN (VxLAN) configuration information for networks they should not have permission to manage. The flaw is categorized under [CWE-425] Direct Request (Forced Browsing), where the application fails to enforce authorization checks for sensitive endpoints. Siemens documented the issue in Siemens Security Advisory SSA-381581.

Critical Impact
Unauthorized modification of VxLAN network configuration can disrupt remote connectivity for industrial control systems and OT environments relying on SINEMA Remote Connect.

Affected Products

Siemens SINEMA Remote Connect Server (all versions before V3.2 SP1)
Siemens SINEMA Remote Connect Server 3.2
Siemens SINEMA Remote Connect Server 3.2 HF1

Discovery Timeline

2024-07-09 - CVE-2024-39868 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-39868

Vulnerability Analysis

SINEMA Remote Connect Server provides centralized management of remote connections to industrial equipment. The web interface exposes administrative functionality for defining VxLAN overlays that segment traffic between remote sites. Certain endpoints that perform VxLAN configuration actions do not properly validate the requester's authentication or authorization state. An attacker who can reach the management interface over the network can invoke these endpoints and alter VxLAN definitions belonging to networks outside their assigned scope. The result is unauthorized read and write access to network overlay configuration data that governs how remote sites reach industrial assets.

Root Cause

The root cause is a missing or incomplete server-side authentication check on VxLAN configuration handlers in the web interface. The application relies on client-side or contextual assumptions rather than validating each request against the caller's session and privilege level. This maps to [CWE-425] Direct Request, in which sensitive functions are reachable without proceeding through the intended authentication or authorization flow.

Attack Vector

Exploitation requires network access to the SINEMA Remote Connect Server web interface. No user interaction is required, and the attacker does not need valid credentials for the target VxLAN scope. An attacker sends crafted HTTP requests directly to the affected configuration endpoints. Because SINEMA Remote Connect Server frequently sits at the boundary between corporate IT and industrial networks, exposure to this flaw can allow lateral changes across OT segmentation. No public proof-of-concept exploit is currently listed, and the vulnerability is not present on the CISA Known Exploited Vulnerabilities catalog.

No verified exploit code is publicly available. Refer to Siemens Security Advisory SSA-381581 for vendor technical details.

Detection Methods for CVE-2024-39868

Indicators of Compromise

Unexpected VxLAN configuration changes in the SINEMA Remote Connect Server audit logs.
HTTP requests to VxLAN configuration endpoints originating from unauthenticated sessions or unusual source addresses.
Newly appearing VxLAN identifiers, tunnel endpoints, or network mappings that no administrator created.

Detection Strategies

Compare current VxLAN configuration exports against a known-good baseline to identify unauthorized modifications.
Alert on any successful configuration-changing HTTP requests to the management interface that lack a corresponding authenticated administrator session.
Correlate web interface access logs with administrator login events to surface configuration activity without matching authentication.

Monitoring Recommendations

Forward SINEMA Remote Connect Server web and audit logs to a centralized SIEM for retention and correlation.
Monitor network flows to and from the SINEMA management interface, alerting on access from segments that should not reach it.
Track version and patch status of all SINEMA Remote Connect Server instances to confirm remediation coverage.

How to Mitigate CVE-2024-39868

Immediate Actions Required

Upgrade SINEMA Remote Connect Server to V3.2 SP1 or later as directed by Siemens.
Restrict network access to the SINEMA Remote Connect Server web interface to trusted administrative hosts only.
Review VxLAN configuration for unauthorized entries and revert any changes that cannot be attributed to legitimate administrators.

Patch Information

Siemens has released V3.2 SP1 to address CVE-2024-39868. Details, download links, and vendor guidance are published in Siemens Security Advisory SSA-381581. Apply the update following Siemens' documented upgrade procedure and validate service availability after patching.

Workarounds

Place the SINEMA Remote Connect Server behind a firewall that limits management interface access to a dedicated administrative VLAN or jump host.
Enforce network segmentation between OT and IT environments so untrusted networks cannot reach the SINEMA web interface.
Audit and export current VxLAN configuration regularly so unauthorized modifications can be identified and rolled back quickly.

bash

# Example firewall restriction (illustrative)
# Allow only the admin jump host to reach the SINEMA web interface
iptables -A INPUT -p tcp --dport 443 -s 10.10.0.25 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP