2025 Shelly Pro 3EM ICS Flaw Exposes Modbus Devices to DoS
In November 2025, a critical Out-of-Bounds Read vulnerability (CVE-2025-12056) was disclosed in the Shelly Pro 3EM, a smart DIN rail switch used in industrial control systems worldwide. Security researchers revealed that a specially crafted Modbus request allows attackers on the adjacent network to trigger an illegal memory access, causing a denial-of-service condition by repeatedly rebooting the device. All versions of the Pro 3EM are affected, including deployments across critical manufacturing sectors. Shelly did not issue an official response, leaving users to rely on CISA defensive guidance. This incident exemplifies the growing risk of targeted vulnerabilities in widely deployed OT (operational technology) and industrial IoT devices. As criminals and nation-state actors increasingly focus on ICS and critical infrastructure, maintaining robust segmentation, access controls, and secure outbound communications is more relevant than ever.
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