An exploitable denial-of-service vulnerability exists in the iocheckd service ‘’I/O-Chec’’ functionality of WAGO PFC 200 Firmware versions 03.01.07(13) and 03.00.39(12), and WAGO PFC 100 Firmware version 03.00.39(12). A specially crafted set of packets can cause a denial of service, resulting in the device entering an error state where it ceases all network communications. An attacker can send unauthenticated packets to trigger this vulnerability.