CVE-2019-6575 in SIMATIC CP443-1 OPC UA
Summary
by MITRE
A vulnerability has been identified in SIMATIC CP 443-1 OPC UA (All versions), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions < V2.7), SIMATIC HMI Comfort Outdoor Panels 7" & 15" (incl. SIPLUS variants) (All versions < V15.1 Upd 4), SIMATIC HMI Comfort Panels 4" - 22" (incl. SIPLUS variants) (All versions < V15.1 Upd 4), SIMATIC HMI KTP Mobile Panels KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V15.1 Upd 4), SIMATIC IPC DiagMonitor (All versions < V5.1.3), SIMATIC NET PC Software V13 (All versions), SIMATIC NET PC Software V14 (All versions < V14 SP1 Update 14), SIMATIC NET PC Software V15 (All versions), SIMATIC RF188C (All versions < V1.1.0), SIMATIC RF600R family (All versions < V3.2.1), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions >= V2.5 < V2.6.1), SIMATIC S7-1500 Software Controller (All versions between V2.5 (including) and V2.7 (excluding)), SIMATIC WinCC OA (All versions < V3.15 P018), SIMATIC WinCC Runtime Advanced (All versions < V15.1 Upd 4), SINEC NMS (All versions < V1.0 SP1), SINEMA Server (All versions < V14 SP2), SINUMERIK OPC UA Server (All versions < V2.1), TeleControl Server Basic (All versions < V3.1.1). Specially crafted network packets sent to affected devices on port 4840/tcp could allow an unauthenticated remote attacker to cause a denial of service condition of the OPC communication or crash the device. The security vulnerability could be exploited by an attacker with network access to the affected systems. Successful exploitation requires no system privileges and no user interaction. An attacker could use the vulnerability to compromise availability of the OPC communication.
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Analysis
by VulDB Data Team • 06/03/2026
This vulnerability represents a critical denial-of-service condition affecting numerous Siemens industrial control systems and OPC UA implementations. The flaw exists within the OPC UA communication stack of various Siemens products including S7-1500 controllers, WinCC runtime environments, and network communication devices. The vulnerability specifically targets port 4840/tcp which is the standard port for OPC UA communication, making it particularly dangerous in industrial environments where continuous operation is critical. The issue stems from inadequate input validation in the OPC UA protocol implementation, allowing specially crafted network packets to trigger unexpected behavior in the affected systems.
The technical nature of this vulnerability aligns with CWE-129, Input Validation, and CWE-400, Uncontrolled Resource Consumption, as the malformed packets can cause the targeted devices to consume excessive resources or enter unstable states. The flaw operates at the network protocol level where the OPC UA server fails to properly handle malformed or maliciously constructed packets sent to the standard communication port. This allows an unauthenticated remote attacker to exploit the vulnerability from any network location with access to the target systems, without requiring any special privileges or user interaction. The exploitation mechanism leverages the inherent design of the OPC UA protocol implementation rather than any specific system weakness.
The operational impact of this vulnerability extends beyond simple service disruption, as OPC UA communication forms the backbone of industrial automation and monitoring systems. When exploited, the vulnerability can cause complete loss of communication capabilities between industrial control systems and their monitoring interfaces, potentially leading to production halts, safety system failures, or complete operational outages. The affected systems include critical infrastructure components such as the SIMATIC S7-1500 CPU family, WinCC runtime environments, and various network communication devices that are fundamental to industrial process control. Organizations using these systems face significant risk of operational disruption, particularly in environments where real-time communication and control are essential for safety and productivity.
Mitigation strategies should focus on network segmentation and access control measures to prevent unauthorized network access to the affected systems. Implementing network filtering rules to block access to port 4840/tcp from untrusted networks represents the most effective immediate response, though this may require careful planning to avoid disrupting legitimate communications. Organizations should also consider applying official patches from Siemens as they become available, which typically address the underlying input validation issues in the OPC UA implementations. The vulnerability demonstrates the importance of securing industrial control systems at the network level, as highlighted by ATT&CK technique T1190, Exploit Public-Facing Application, which specifically addresses vulnerabilities in network services that are accessible from external networks. Regular network monitoring and anomaly detection should be implemented to identify potential exploitation attempts, while maintaining detailed logs of OPC UA communication traffic for forensic analysis.