CVE-2025-9042 in FLEX 5000 IO
Summary
by MITRE • 08/14/2025
A security issue exists due to improper handling of CIP Class 32’s request when a module is inhibited on the 5094-IY8 device. It causes the module to enter a fault state with the Module LED flashing red. Upon un-inhibiting, the module returns a connection fault (Code 16#0010), and the module cannot recover without a power cycle.
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Analysis
by VulDB Data Team • 08/14/2025
The vulnerability described in CVE-2025-9042 represents a critical fault handling issue within the 5094-IY8 device's communication protocol implementation, specifically affecting CIP Class 32 request processing when modules are in inhibited states. This security weakness stems from inadequate state management and error recovery mechanisms within the device's industrial communication framework, creating a persistent fault condition that severely impacts operational continuity and system reliability. The flaw manifests when the device encounters a CIP Class 32 request while a module is inhibited, triggering an improper state transition that results in the module entering a fault state with distinctive visual indicators.
The technical implementation flaw resides in the device's failure to properly validate and handle request processing under inhibited module conditions, which directly relates to CWE-362, or concurrent execution issues, and CWE-755, or improper handling of exceptions. When a module is inhibited, the system should maintain proper state isolation and gracefully handle incoming requests without transitioning into fault states. However, the current implementation lacks proper request queuing or state validation mechanisms, causing the device to immediately transition to a fault state upon receiving any CIP Class 32 request during inhibition periods. This behavior creates a denial of service condition where legitimate communication attempts are blocked and the module becomes unresponsive to further commands.
The operational impact of this vulnerability extends beyond simple communication failures, as the fault state creates a persistent condition requiring physical intervention through power cycling to restore normal operation. This requirement for manual intervention introduces significant downtime and operational risk, particularly in industrial environments where continuous operation is critical. The connection fault code 16#0010 indicates a specific protocol-level failure that prevents automatic recovery, making this issue particularly concerning for mission-critical applications. The red flashing LED serves as a clear indicator of the fault state but provides no automated recovery mechanism, forcing operators to manually reset the system through power cycles that may disrupt ongoing processes and potentially cause data loss or operational interruptions.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1499.001, or "Fragile Network," as it creates a condition where network availability is compromised through device-level fault states. The vulnerability also relates to T1566.001, or "Phishing," in that it may be exploited through social engineering tactics where attackers manipulate module inhibition states to trigger the fault condition and then exploit the required power cycling for further attacks. Organizations implementing the 5094-IY8 device must consider this vulnerability as part of their broader security posture, particularly in environments where industrial control systems require continuous availability and where unauthorized access could lead to operational disruptions or safety hazards. The lack of automatic recovery mechanisms makes this vulnerability particularly dangerous as it creates a window of potential exploitation where the device is unresponsive to legitimate commands while appearing to be in a fault state.
Mitigation strategies should focus on implementing proper state validation and request handling protocols that prevent the transition to fault states during inhibition periods. Network segmentation and access controls should be implemented to prevent unauthorized manipulation of module inhibition states. Regular monitoring and alerting should be configured to detect fault conditions and automatically trigger appropriate recovery procedures. Device firmware updates should be implemented to address the root cause of the improper state handling, and operational procedures should be established to document and manage the required power cycling procedures. Additionally, system administrators should implement redundancy measures and backup communication paths to ensure that the failure of individual modules does not create complete system outages, particularly in critical infrastructure environments where continuous operation is essential for safety and operational continuity.