CVE-2025-26411 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) affecting Wattsense Bridge devices. The flaw resides in the Plugin Manager component of the device's web interface, which insufficiently validates uploaded files. An attacker with valid user credentials can upload malicious Python scripts, which the device executes, resulting in remote root access. This level of access allows full control over the device, enabling attackers to manipulate device functions, exfiltrate data, or pivot to other network segments. The vulnerability requires authentication but no additional user interaction, making it relatively straightforward for insiders or compromised users to exploit. The issue affects all versions prior to BSP 6.1.0, where the vendor has implemented proper file validation and upload restrictions. The CVSS 3.1 score of 8.8 indicates a high-severity vulnerability with network attack vector, low attack complexity, and high impact on confidentiality, integrity, and availability. Although no public exploits are known, the potential for severe operational disruption and unauthorized control is significant, especially in environments where Wattsense Bridges manage critical building automation or IoT infrastructure.

For European organizations, this vulnerability poses a serious risk to operational technology and building management systems that rely on Wattsense Bridge devices. Successful exploitation can lead to full device compromise, allowing attackers to disrupt building automation, manipulate environmental controls, or use the device as a foothold for lateral movement within corporate networks. This can result in data breaches, service outages, and safety hazards. The high CVSS score reflects the potential for widespread impact, especially in sectors such as energy management, smart buildings, and industrial IoT deployments prevalent across Europe. Organizations in critical infrastructure sectors may face regulatory and compliance consequences if such vulnerabilities are exploited. The need for authentication limits exposure to some extent, but insider threats or credential compromise remain significant concerns. The absence of known exploits in the wild provides a window for remediation before active exploitation occurs.

European organizations should immediately verify the firmware version of all Wattsense Bridge devices and upgrade to BSP 6.1.0 or later to remediate this vulnerability. Access to the Plugin Manager web interface must be restricted using network segmentation, VPNs, or firewall rules to limit exposure to authorized personnel only. Implement strong authentication mechanisms, including multi-factor authentication (MFA), to reduce the risk of credential compromise. Regularly audit user accounts and permissions to ensure only necessary users have access to the device management interface. Monitor logs for unusual upload activities or unauthorized access attempts. Employ network intrusion detection systems (NIDS) to detect anomalous behavior indicative of exploitation attempts. Additionally, consider isolating building automation networks from corporate IT networks to contain potential breaches. Establish incident response plans specific to IoT and building management systems to quickly address any detected compromise.