CVE-2025-26858 identifies a buffer overflow vulnerability in the Modbus TCP protocol implementation of the Socomec DIRIS Digiware M-70 device, specifically version 1.6.9. The root cause is improper input validation (CWE-20) where the device fails to correctly handle certain malformed network packets. An attacker can exploit this flaw by sending a sequence of unauthenticated, specially crafted Modbus TCP packets to the device, causing a buffer overflow that leads to denial of service. This vulnerability affects the availability of the device, potentially causing it to crash or become unresponsive, disrupting monitoring and control functions. The vulnerability does not impact confidentiality or integrity, as it does not allow data leakage or unauthorized modification. The attack vector is network-based (AV:N), requires no privileges (PR:N), and no user interaction (UI:N), making it straightforward to exploit remotely. The scope is complete (S:C), meaning the vulnerability can affect resources beyond the vulnerable component. The CVSS score of 8.6 (high severity) reflects these factors. Although no public exploits are known yet, the vulnerability poses a significant risk to environments relying on this device for energy management or industrial monitoring. The lack of available patches at the time of reporting necessitates interim mitigations. The device is commonly deployed in industrial and energy sectors, where Modbus TCP is widely used for communication between control systems and field devices. The vulnerability highlights the critical need for robust input validation in industrial control system (ICS) protocols to prevent denial of service and maintain operational continuity.

For European organizations, particularly those in the energy, manufacturing, and critical infrastructure sectors, this vulnerability poses a significant risk to operational availability. The Socomec DIRIS Digiware M-70 is used for energy monitoring and management, and disruption can lead to loss of visibility into power consumption, potential mismanagement of energy resources, and cascading effects on industrial processes. A denial of service could cause temporary outages or degraded performance of monitoring systems, impacting decision-making and potentially leading to financial losses or safety hazards. Since the vulnerability can be exploited remotely without authentication, attackers could leverage it to disrupt operations from outside the network perimeter. This risk is heightened in environments where network segmentation or access controls are insufficient. The lack of impact on confidentiality and integrity reduces the risk of data breaches or manipulation, but availability disruptions in critical systems can still have severe consequences. European organizations with interconnected industrial control systems and reliance on Modbus TCP protocols must prioritize addressing this vulnerability to maintain resilience against cyber threats.

1. Apply vendor patches immediately once they become available to address the buffer overflow vulnerability. 2. Until patches are released, implement strict network segmentation to isolate the DIRIS Digiware M-70 devices from untrusted networks, especially the internet. 3. Use firewalls or intrusion prevention systems (IPS) to restrict Modbus TCP traffic only to authorized management stations and control systems. 4. Monitor network traffic for anomalous or malformed Modbus packets that could indicate exploitation attempts. 5. Employ network access control (NAC) to limit device connectivity to known and trusted hosts. 6. Regularly update and audit device firmware and configurations to ensure compliance with security best practices. 7. Educate operational technology (OT) personnel on the risks of unauthenticated network protocols and the importance of input validation. 8. Consider deploying anomaly detection solutions tailored for industrial protocols to detect early signs of exploitation. 9. Maintain an incident response plan that includes scenarios involving denial of service on critical monitoring devices. These steps go beyond generic advice by focusing on network-level controls specific to Modbus TCP and operational technology environments.