Cisco NX-OS 4.2, 5.0, 5.1, and 5.2 on Nexus 7000 series switches, when the High Availability (HA) policy is configured for Reset, allows remote attackers to cause a denial of service (device reset) via a malformed Cisco Discovery Protocol (CDP) packet, aka Bug IDs CSCtk34535 and CSCtk19132.
http://www.securitytracker.com/id?1027352
http://www.4salesbyself.com/troubleshooting-random-nexus-reboots.aspx