CVE-2025-26389 Overview
CVE-2025-26389 is an unauthenticated remote code execution vulnerability in Siemens OZW672 and OZW772 web servers. These devices serve as communication gateways for building automation and heating control systems. The web service fails to sanitize input parameters supplied to the exportDiagramPage endpoint. An unauthenticated remote attacker can exploit this flaw to execute arbitrary operating system commands with root privileges. The issue is tracked under CWE-78 (Improper Neutralization of Special Elements used in an OS Command). Siemens published advisory SSA-047424 addressing the issue.
Critical Impact
Unauthenticated attackers reachable over the network can fully compromise affected devices with root-level command execution, gaining persistent control over building automation infrastructure.
Affected Products
- Siemens OZW672 (all versions prior to V8.0)
- Siemens OZW772 (all versions prior to V8.0)
- Associated OZW672 and OZW772 firmware images
Discovery Timeline
- 2025-05-13 - CVE-2025-26389 published to NVD
- 2025-10-06 - Last updated in NVD database
Technical Details for CVE-2025-26389
Vulnerability Analysis
The vulnerability resides in the embedded web service running on Siemens OZW672 and OZW772 web servers. The exportDiagramPage endpoint accepts input parameters that are passed to an underlying operating system shell without proper neutralization. An attacker can inject shell metacharacters or additional commands into a request to that endpoint. The injected payload is then executed by the device with root privileges. Because the endpoint is exposed by the device web service and requires no authentication, exploitation only requires network reachability to the device. The classification under CWE-78 confirms the root issue is OS command injection rather than memory corruption.
Root Cause
The web service does not sanitize or validate input parameters required by the exportDiagramPage handler before passing them to a command interpreter. Untrusted attacker-controlled data crosses directly into a privileged execution context, violating standard input handling and least-privilege practices.
Attack Vector
An attacker sends a crafted HTTP request containing malicious parameters to the exportDiagramPage endpoint over the network. No credentials, user interaction, or prior access are required. Successful exploitation yields arbitrary command execution as root, enabling firmware tampering, lateral movement into OT segments, deployment of persistence mechanisms, and disruption of heating or building control logic.
No verified public proof-of-concept code is referenced in the advisory. Refer to the Siemens Security Advisory SSA-047424 for technical details.
Detection Methods for CVE-2025-26389
Indicators of Compromise
- HTTP requests to the exportDiagramPage endpoint containing shell metacharacters such as ;, |, &, backticks, or $() substitution patterns.
- Unexpected outbound network connections originating from OZW672 or OZW772 devices to attacker-controlled infrastructure.
- Modified configuration files, new cron entries, or unfamiliar processes running on the device after web service activity.
Detection Strategies
- Inspect web server and reverse proxy logs in front of OZW devices for anomalous query strings targeting exportDiagramPage.
- Deploy network intrusion detection signatures that flag command injection patterns directed at OZW672/OZW772 management interfaces.
- Baseline normal administrative traffic to the devices and alert on requests from unexpected source IP ranges, especially from outside the OT management VLAN.
Monitoring Recommendations
- Continuously monitor north-south and east-west traffic to building automation gateways using OT-aware network sensors.
- Forward device and perimeter logs to a centralized analytics platform for correlation against known command injection indicators.
- Track firmware versions across the OZW672 and OZW772 fleet to identify unpatched devices that remain exposed.
How to Mitigate CVE-2025-26389
Immediate Actions Required
- Upgrade OZW672 and OZW772 devices to firmware V8.0 or later as instructed in Siemens Security Advisory SSA-047424.
- Identify all OZW672 and OZW772 devices in the environment, including those reachable through remote service portals or VPN concentrators.
- Remove direct internet exposure of device management interfaces and restrict access to a hardened jump host.
Patch Information
Siemens addressed the issue in firmware version V8.0 for both OZW672 and OZW772 product lines. Asset owners should plan and validate the firmware update following Siemens' documented upgrade procedure. Confirm post-upgrade that the exportDiagramPage endpoint no longer accepts unsanitized input by reviewing release notes in advisory SSA-047424.
Workarounds
- Place OZW672 and OZW772 devices behind a firewall and allow management access only from explicitly trusted administrative networks.
- Disable or block external access to the device web service until firmware V8.0 is applied.
- Apply Siemens' general operational guidelines for industrial security, including network segmentation between IT, OT, and building automation zones.
# Example firewall restriction to limit access to OZW management interface
# Replace 10.10.50.0/24 with your dedicated OT admin subnet
# Replace 192.0.2.10 with the OZW device address
iptables -A FORWARD -p tcp -s 10.10.50.0/24 -d 192.0.2.10 --dport 443 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 443 -j DROP
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
