CVE-2026-25817 affects HMS Networks Ewon Flexy devices running firmware versions before 15.0s4, and Cosy+ devices running firmware 22.xx before 22.1s6 and 23.xx before 23.0s3. The vulnerability stems from improper neutralization of special elements used in operating system commands, which allows an attacker with low privilege access and valid credentials on the gateway to execute arbitrary OS commands remotely. This is a classic command injection vulnerability categorized under CWE-94, where user-supplied input is not properly sanitized before being incorporated into system-level commands. The flaw enables attackers to escalate their privileges and potentially take full control of the affected device. The CVSS v3.1 base score is 8.8, reflecting high impact on confidentiality, integrity, and availability, with network attack vector, low attack complexity, and no user interaction required. Although no public exploits are known at this time, the vulnerability poses a significant risk to industrial and operational technology environments that rely on these devices for secure remote access and data communication.

Successful exploitation of this vulnerability can lead to full remote compromise of affected Ewon Flexy and Cosy+ gateways. Attackers could execute arbitrary commands, potentially leading to data theft, manipulation of industrial control processes, disruption of network communications, or pivoting to other internal systems. Given these devices are commonly used in industrial automation and remote monitoring, the impact extends to critical infrastructure sectors such as manufacturing, energy, and utilities. The compromise could result in operational downtime, safety hazards, financial losses, and damage to organizational reputation. The requirement for valid credentials limits the attack surface but does not eliminate risk, especially in environments where credential management is weak or where attackers have already gained initial access.

Organizations should immediately verify the firmware versions of their HMS Networks Ewon Flexy and Cosy+ devices and upgrade to firmware versions 15.0s4 or later for Flexy, 22.1s6 or later for Cosy+ 22.xx, and 23.0s3 or later for Cosy+ 23.xx. If immediate patching is not possible, restrict network access to these devices to trusted management networks only and enforce strong authentication policies, including multi-factor authentication where supported. Regularly audit and rotate credentials to reduce the risk of credential compromise. Implement network segmentation to isolate these gateways from critical systems and monitor device logs for unusual command execution or access patterns. Additionally, consider deploying intrusion detection systems capable of identifying command injection attempts targeting these devices. Vendors and users should collaborate to ensure timely updates and share threat intelligence regarding any emerging exploits.