The RealServer RealSubscriber on Cisco devices running Application and Content Networking System (ACNS) 5.1 allow remote attackers to cause a denial of service (CPU consumption) via malformed packets.
https://exchange.xforce.ibmcloud.com/vulnerabilities/19469
http://www.securityfocus.com/bid/12648
http://www.kb.cert.org/vuls/id/579240
http://www.cisco.com/warp/public/707/cisco-sa-20050224-acnsdos.shtml