CVE-2026-12659 in FLEX 5000 EtherNet IP Adapter
Summary
by MITRE • 07/14/2026
A denial-of-service security issue exists in the affected products. The security issue stems from improper handling of exceptional conditions when processing crafted CIP packets sent to the adapter. A power cycle is required to recover the module and associated I/O.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical denial-of-service condition that affects industrial control systems through improper exception handling mechanisms within communication protocols. The flaw specifically manifests when processing specially crafted Common Industrial Protocol packets that exploit inadequate error management within the network adapter firmware. The issue demonstrates characteristics consistent with CWE-400 weakness category, which encompasses unspecified errors in resource management and exception handling that can lead to system instability and operational disruption. When maliciously constructed CIP packets are transmitted to the affected adapter, the system fails to properly manage these exceptional conditions, resulting in complete module failure that requires physical power cycling to restore normal operations.
The technical implementation of this vulnerability reveals a fundamental flaw in the protocol processing stack where error conditions are not gracefully handled or contained within appropriate exception boundaries. This type of vulnerability falls under the ATT&CK framework's T1499.004 technique category, which involves network disruption through denial-of-service attacks targeting industrial control systems. The inability to recover from malformed packet processing without manual intervention indicates a lack of robust fault tolerance mechanisms in the system architecture, creating significant operational risks for critical infrastructure deployments where continuous operation is essential.
The operational impact of this vulnerability extends beyond simple service interruption to encompass potential production line shutdowns and safety system compromises in industrial environments. Recovery requires physical power cycling of the module, which may not be feasible during critical operations or in remote locations where immediate access is impossible. This dependency on manual intervention creates substantial downtime risks for manufacturing processes, automated systems, and control networks where continuous operation is paramount. The vulnerability affects the availability aspect of the CIA triad by compromising system uptime and operational reliability.
Mitigation strategies should focus on implementing network segmentation to isolate affected devices from critical control systems while applying firmware updates that address the exception handling flaws in CIP packet processing. Network monitoring solutions should be deployed to detect anomalous packet patterns that may indicate exploitation attempts, as well as implementing intrusion detection systems specifically configured to identify malformed CIP traffic. Organizations should also establish emergency recovery procedures that minimize downtime impact and consider implementing redundant communication paths to maintain operational continuity during potential attacks. The vulnerability underscores the importance of robust error handling in industrial network protocols and highlights the need for comprehensive security testing of control system communications to prevent similar issues in other industrial environments.