Cisco IOS XE 3.8S(.2) and earlier does not properly use a DHCP pool during assignment of an IP address, which allows remote authenticated users to cause a denial of service (device reload) via an AAA packet that triggers an address requirement, aka Bug ID CSCuh04949.
http://tools.cisco.com/security/center/viewAlert.x?alertId=31860
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2013-6692