CVE-2026-82784 in Remote IO Coupler Unit CPSN-MCB271-*
Summary
by MITRE • 09/14/2026
Missing authentication for critical function vulnerability exists in Remote I/O Coupler Unit (Server Type) CPSN-MCB271-*. An attacker may execute a REST API without authentication, which could allow the attacker to retrieve I/O values and/or control the output.
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Analysis
by VulDB Data Team • 09/14/2026
The identified vulnerability represents a critical failure in access control mechanisms within the Remote I/O Coupler Unit model CPSN-MCB271-*, specifically affecting its server-type configuration. This security flaw is classified under CWE-306, which denotes missing authentication for a critical function. In industrial automation environments, such devices serve as vital interfaces between programmable logic controllers and field instruments, managing the exchange of digital and analog signals. The absence of mandatory authentication for specific REST API endpoints means that any entity capable of reaching the device over the network can interact with these services without providing valid credentials or session tokens. This lack of enforcement fundamentally undermines the principle of least privilege and fails to verify the identity of the requesting party before granting access to sensitive operational data or control commands.
From a technical perspective, the vulnerability allows an unauthenticated attacker to execute REST API calls that are intended for authorized administrators or operators only. These APIs typically expose endpoints responsible for reading current input values from connected sensors and writing output states to actuators or indicators. Because authentication is not required, the attack surface expands significantly beyond authenticated users who might have legitimate but limited access rights. An adversary can leverage standard HTTP methods such as GET to retrieve real-time process data, which may include sensitive operational metrics that reveal production rates, machine statuses, or environmental conditions. Furthermore, POST or PUT requests can be utilized to alter output states, effectively allowing the attacker to toggle relays, trigger alarms, or manipulate physical processes without detection by traditional perimeter defenses that rely on network segmentation rather than application-layer authentication checks.
The operational impact of this vulnerability is severe due to its direct influence on both confidentiality and integrity within the industrial control system. The ability to retrieve I/O values compromises the confidentiality of proprietary process information, potentially allowing competitors or malicious actors to infer production schedules or identify vulnerabilities in adjacent systems based on state changes. More critically, the capacity to control outputs poses a significant risk to safety and availability. An attacker could cause physical damage by forcing actuators into unsafe positions, disrupt manufacturing lines by stopping critical machinery, or create hazardous conditions if the controlled devices are part of safety-critical processes such as pressure relief valves or emergency shutdown systems. This aligns with MITRE ATT&CK for ICS techniques T1526, which involves cloud service discovery and exploitation, although in this context it applies to local network-based REST API abuse, and potentially T0849 if the manipulation leads to physical harm or operational disruption.
Mitigation strategies must prioritize immediate remediation of the authentication gap while implementing defense-in-depth measures to limit exposure. The primary corrective action is to enforce strict authentication requirements on all REST API endpoints exposed by the CPSN-MCB271-*, ensuring that every request includes valid credentials verified against a secure identity provider or local user database. If possible, multi-factor authentication should be enabled for administrative access. Additionally, network segmentation plays a crucial role in reducing risk; these devices should reside in isolated zones with strict firewall rules permitting API traffic only from authorized management stations and PLCs. Implementing web application firewalls can also help by inspecting incoming requests for anomalies or unauthorized patterns before they reach the device firmware. Regular security audits and penetration testing focused on industrial protocols and REST interfaces are recommended to identify similar misconfigurations across other connected assets in the facility.