The encryption functionality in the Virtual Supervisor Module (VSM) to Virtual Ethernet Module (VEM) communication component in Cisco NX-OS on the Nexus 1000V does not properly authenticate VSM/VEM packets, which allows remote attackers to disable packet-level encryption and integrity protection via crafted packets, aka Bug ID CSCud14710.
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2013-1209