An exploitable denial of service vulnerability exists in the ENIP Request Path Logical Segment functionality of Allen-Bradley Flex IO 1794-AENT/B 4.003. A specially crafted network request can cause a loss of communications with the device resulting in denial-of-service. An attacker can send a malicious packet to trigger this vulnerability by sending an Electronic Key Segment with less than 0x18 bytes following the Key Format field.