Cisco NX-OS 4.2.x before 4.2(1)SV1(5.1) on Nexus 1000v series switches; 4.x and 5.0.x before 5.0(2)N1(1) on Nexus 5000 series switches; and 4.2.x before 4.2.8, 5.0.x before 5.0.5, and 5.1.x before 5.1.1 on Nexus 7000 series switches allows remote attackers to cause a denial of service (netstack process crash and device reload) via a malformed IP packet, aka Bug IDs CSCti23447, CSCti49507, and CSCtj01991.