CVE-2017-12093
An exploitable insufficient resource pool vulnerability exists in the session communication functionality of Allen Bradley Micrologix 1400 Series B Firmware 21.2 and before. A specially crafted stream of packets can cause a flood of the session resource pool resulting in legitimate connections to the PLC being disconnected. An attacker can send unauthenticated packets to trigger this vulnerability.
Source: CVE-2017-12093