CVE-2026-25817 is a remote code execution vulnerability found in HMS Networks Ewon Flexy and Cosy+ industrial gateway devices. These devices are commonly used for secure remote access and monitoring of industrial control systems (ICS) and operational technology (OT) networks. The vulnerability arises from improper neutralization of special elements in operating system commands, which allows an attacker with low privilege access and valid credentials to inject and execute arbitrary OS commands on the gateway. This flaw exists in Flexy firmware versions prior to 15.0s4, Cosy+ firmware 22.xx prior to 22.1s6, and Cosy+ firmware 23.xx prior to 23.0s3. Exploitation requires authentication but does not require elevated privileges beyond low-level user access, lowering the barrier for attackers who have obtained credentials through phishing, credential stuffing, or insider threats. Successful exploitation could lead to full compromise of the gateway device, enabling attackers to pivot into industrial networks, disrupt operations, or exfiltrate sensitive data. No public exploits or patches are currently documented, indicating the need for proactive mitigation. The vulnerability highlights the importance of input validation and command sanitization in embedded device firmware to prevent injection attacks.

The impact of CVE-2026-25817 is significant for organizations using HMS Networks Ewon Flexy and Cosy+ devices, especially in industrial, manufacturing, energy, and critical infrastructure sectors. Remote code execution on these gateways can lead to full device compromise, allowing attackers to manipulate industrial processes, disrupt monitoring and control systems, or use the device as a foothold for lateral movement within OT networks. Confidentiality, integrity, and availability of industrial control systems could be severely affected. Given the devices’ role in secure remote access, exploitation could also undermine network segmentation and security boundaries. The requirement for valid credentials limits exploitation to attackers who have already gained some level of access, but the low privilege needed increases risk from insider threats or credential compromise. The absence of known exploits suggests limited current active attacks, but the vulnerability presents a high-risk vector if weaponized. Organizations relying on these devices should consider the potential for operational disruption, safety hazards, and data breaches.

To mitigate CVE-2026-25817, organizations should: 1) Immediately verify the firmware versions of all Ewon Flexy and Cosy+ devices and plan upgrades to versions 15.0s4 or later for Flexy, 22.1s6 or later for Cosy+ 22.xx, and 23.0s3 or later for Cosy+ 23.xx once patches are released. 2) Restrict and monitor access to these gateways, enforcing strong authentication mechanisms and limiting credential distribution to trusted personnel only. 3) Implement network segmentation to isolate these devices from broader enterprise and OT networks, minimizing lateral movement opportunities. 4) Monitor device logs and network traffic for unusual command execution patterns or authentication anomalies that could indicate exploitation attempts. 5) Employ multi-factor authentication (MFA) where supported to reduce risk from credential compromise. 6) Conduct regular security audits and penetration tests focused on gateway devices to identify potential weaknesses. 7) Engage with HMS Networks support or security advisories to receive timely updates and patches. 8) Consider deploying intrusion detection systems tailored for industrial protocols to detect abnormal activity. These steps go beyond generic advice by focusing on firmware version control, access management, and network architecture specific to industrial gateway devices.