The IP Service Level Agreement (IP SLA) functionality in Cisco IOS 15.1, and IOS XE 2.1.x through 3.3.x, allows remote attackers to cause a denial of service (memory corruption and device reload) via malformed IP SLA packets, aka Bug ID CSCtk67073.
http://www.securitytracker.com/id?1026120
http://www.cisco.com/en/US/products/products_security_advisory09186a0080b95d4c.shtml
http://tools.cisco.com/security/center/viewAlert.x?alertId=24122