CVE-2026-9653 in Communication Module
Summary
by MITRE • 07/14/2026
A denial-of-service security issue exists across all the 1756-EN2, EN3, and ENBT communication module due to improper validation of CIP Implicit Connection packets. An attacker on the network can exploit this by sending crafted packets to continuously disrupt device connections, though device connections will recover immediately after.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability affects the 1756-EN2, 1756-EN3, and 1756-ENBT communication modules which are part of Rockwell Automation's Ethernet I/O family designed for industrial control systems. The flaw stems from inadequate validation mechanisms within the Common Industrial Protocol (CIP) Implicit Connection handling process, creating a pathway for malicious network traffic to disrupt normal operations. The vulnerability is categorized under CWE-20 as "Improper Input Validation" and aligns with ATT&CK technique T1498.001 for "Network Denial of Service" within the context of industrial control systems.
The technical implementation of this flaw occurs when the communication modules receive CIP Implicit Connection packets that lack proper validation checks. These packets contain connection parameters and data structures that should be rigorously validated before processing, but due to insufficient validation routines, maliciously crafted packets can cause the modules to malfunction or become unresponsive. The vulnerability specifically impacts the implicit connection establishment process within the CIP protocol stack where connection requests are handled without adequate sanitization of input parameters.
Operationally, this vulnerability presents a significant risk to industrial environments as it enables attackers to continuously disrupt device communications through network-based attacks. While the affected devices demonstrate automatic recovery capabilities following disruption events, the persistent nature of the attack can lead to extended periods of operational degradation and potential cascading failures in control system operations. The repeated disruption cycle can cause production downtime, data loss, and compromise overall system reliability in critical infrastructure environments.
Mitigation strategies should focus on network segmentation and access control measures to limit unauthorized access to these communication modules. Implementing network monitoring solutions that can detect anomalous packet patterns and establishing firewall rules to restrict CIP communication traffic can help reduce exposure. Additionally, applying vendor-provided firmware updates and implementing network intrusion detection systems specifically designed for industrial protocols can provide layered protection against exploitation attempts. Organizations should also consider operational procedures for rapid incident response and system recovery protocols to minimize potential impact during attack scenarios.