Cisco IOS 11.x and 12.0 with ATM support allows attackers to cause a denial of service via the undocumented Interim Local Management Interface (ILMI) SNMP community string.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6169
http://www.cisco.com/warp/public/707/ios-snmp-ilmi-vuln-pub.shtml