CVE-2025-11743: CIP Protocol DoS Vulnerability

CVE-2025-11743 Overview

A denial-of-service vulnerability exists in Rockwell Automation industrial control systems that occurs when a malformed CIP (Common Industrial Protocol) forward open message is sent. This security issue can result in a major nonrecoverable fault requiring a system restart to recover normal operations.

Critical Impact

Successful exploitation of this vulnerability can cause complete service disruption in affected industrial control systems, requiring manual intervention to restore functionality in critical operational technology (OT) environments.

Affected Products

• Rockwell Automation industrial control systems with CIP protocol support
• Devices processing CIP forward open messages
• Industrial controllers vulnerable to malformed CIP messages

Discovery Timeline

• 2026-01-20 - CVE-2025-11743 published to NVD
• 2026-01-20 - Last updated in NVD database

Technical Details for CVE-2025-11743

Vulnerability Analysis

This vulnerability is classified under CWE-1284 (Improper Validation of Specified Quantity in Input), indicating the affected system fails to properly validate input quantities within CIP forward open messages. The CIP protocol is widely used in industrial automation environments for communication between programmable logic controllers (PLCs), human-machine interfaces (HMIs), and other industrial devices.

The attack requires adjacent network access, meaning an attacker must be on the same network segment as the vulnerable device. This is common in industrial environments where OT networks may have flat architectures or insufficient segmentation from IT networks.

When a specially crafted malformed CIP forward open message is received by the vulnerable device, the improper input validation causes a major nonrecoverable fault. This fault condition persists until the device is manually restarted, making it particularly impactful in environments where continuous operation is critical.

Root Cause

The root cause of CVE-2025-11743 is improper validation of specified quantities within CIP forward open messages (CWE-1284). The affected system does not adequately verify that input parameters in CIP messages fall within expected bounds before processing them. When malformed data with unexpected quantity values is received, the parser or processing logic encounters an unhandled condition that triggers a fatal system fault.

Attack Vector

The attack vector for this vulnerability requires adjacent network access, meaning the attacker must have connectivity to the same local network segment as the target device. The attack does not require authentication or user interaction, and has low attack complexity. An attacker could craft a malicious CIP forward open message containing malformed data designed to trigger the improper validation flaw.

In industrial environments, this could be exploited by:

• An attacker who has gained access to the OT network through compromised workstations or network infrastructure
• Malicious insiders with access to industrial network segments
• Lateral movement from compromised IT systems that have connectivity to OT networks

The vulnerability affects availability only, with no impact on confidentiality or integrity of the system. However, in industrial control environments, loss of availability can have significant operational and safety implications.

Detection Methods for CVE-2025-11743

Indicators of Compromise

• Unexpected device restarts or faults on industrial controllers
• Abnormal CIP traffic patterns on industrial network segments
• Error logs indicating malformed CIP message processing failures
• Sudden loss of connectivity to affected industrial control devices

Detection Strategies

• Deploy network monitoring solutions capable of inspecting CIP protocol traffic for malformed messages
• Configure intrusion detection systems with signatures for anomalous CIP forward open message patterns
• Monitor device health metrics for unexpected fault conditions or restart events
• Implement baseline monitoring for normal CIP traffic volumes and patterns on OT networks

Monitoring Recommendations

• Enable comprehensive logging on industrial network firewalls and switches
• Deploy industrial protocol-aware network detection and response (NDR) solutions
• Monitor for CIP connection establishment anomalies across network segments
• Correlate device fault events with network traffic analysis to identify potential exploitation attempts

How to Mitigate CVE-2025-11743

Immediate Actions Required

• Review the Rockwell Automation Security Advisory SD1770 for specific patch and mitigation guidance
• Implement network segmentation to restrict access to vulnerable devices from untrusted network segments
• Ensure only authorized systems can communicate with industrial controllers via CIP
• Deploy application-layer firewalls capable of inspecting and filtering malformed CIP traffic

Patch Information

Rockwell Automation has released security advisory SD1770 addressing this vulnerability. Administrators should consult the official security advisory for detailed patch availability, affected firmware versions, and specific remediation instructions for their deployed products.

Workarounds

• Implement strict network segmentation to isolate industrial control systems from general network traffic
• Use industrial firewalls or intrusion prevention systems to filter CIP traffic and block malformed messages
• Restrict network access to affected devices to only authorized IP addresses and systems
• Consider disabling unnecessary CIP services or connections where operationally feasible

# Network segmentation configuration example
# Restrict CIP traffic (port 44818) to authorized sources only
iptables -A INPUT -p tcp --dport 44818 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 44818 -j DROP
iptables -A INPUT -p udp --dport 44818 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p udp --dport 44818 -j DROP