UDP Unicast Storm DoS in 1719-AENTR

Executive Summary

CVE-2026-9140 is a denial-of-service (DoS) vulnerability affecting Rockwell Automation's 1718-AENTR and 1719-AENTR EtherNet/IP adapters. The issue occurs due to improper handling of a UDP unicast network storm, which overwhelms the device.

When the device is exposed to such a network storm, it becomes overloaded and loses communication capabilities. To restore functionality, a physical power cycle of the device is required.

• Affected products: 1718-AENTR and 1719-AENTR EtherNet/IP adapters.
• Root cause: CWE-770 (Allocation of Resources Without Limits or Throttling).
• Affected firmware version: 3.011.
• Fixed in firmware version: 3.012.

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Detection Guidance

Detecting this vulnerability on your network or system involves monitoring for signs of a UDP unicast network storm targeting the affected Rockwell Automation 1719-AENTR devices. Since the vulnerability is triggered by improper handling of UDP traffic, you can use network monitoring tools to identify unusual UDP traffic patterns.

• Use Wireshark or tcpdump to capture and analyze UDP traffic. Look for excessive UDP packets directed at the device's IP address. Example command: tcpdump -i eth0 udp and host [device_ip]
• Check the device's status for communication loss or unresponsiveness, which may indicate it has been overloaded by a UDP storm.
• Monitor network bandwidth usage for spikes in UDP traffic that could suggest a network storm.

If the device becomes unresponsive and requires a power cycle to recover, this is a strong indicator that the vulnerability has been exploited.

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Impact Analysis

This vulnerability can have several impacts if exploited:

• Denial-of-service (DoS): The affected device will lose communication and become unresponsive, disrupting operations that rely on it.
• Operational downtime: A power cycle is required to recover the device, which may lead to unplanned downtime in industrial or automation environments.
• Potential safety risks: If the device is part of a critical control system, its failure could lead to unsafe conditions or process interruptions.

The vulnerability can be triggered remotely without authentication, increasing the risk of exploitation by malicious actors.

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Compliance Impact

The impact of this vulnerability on compliance with standards and regulations depends on the context in which the affected devices are used:

• GDPR: If the device processes or transmits personal data and its failure leads to a data breach or loss of data integrity, it could result in non-compliance with GDPR requirements for data protection and availability.
• HIPAA: If the device is used in a healthcare environment to handle protected health information (PHI) and its failure disrupts access to or integrity of PHI, it could violate HIPAA's security and availability rules.
• Industrial standards (e.g., IEC 62443, NIST SP 800-82): The vulnerability may violate requirements for system availability, resilience, and protection against DoS attacks, which are critical in industrial control systems (ICS).

Organizations should assess whether the affected devices are part of systems subject to these regulations and take corrective actions, such as applying the firmware update, to maintain compliance.

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Mitigation Strategies

The primary mitigation step is to upgrade the affected Rockwell Automation 1719-AENTR device to firmware version 3.012 or later, as this version corrects the vulnerability.

• Download and install the corrected firmware version 3.012 from Rockwell Automation's official support channels.

If upgrading is not immediately possible, follow these temporary mitigation steps:

• Isolate the affected device from untrusted networks to prevent exposure to UDP unicast network storms.
• Implement network-level protections such as firewalls or intrusion prevention systems (IPS) to filter or rate-limit UDP traffic directed at the device.
• Follow Rockwell Automation's security best practices, which may include segmenting the network and restricting access to critical devices.

No workarounds are available for this vulnerability, so upgrading the firmware is the recommended long-term solution.

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