Cisco ONS 15327 before 4.1(3), ONS 15454 before 4.6(1), and ONS 15454 SD before 4.1(3) allows remote attackers to cause a denial of service (reset) by not sending the ACK portion of the TCP three-way handshake and sending an invalid response instead.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15265
http://www.securityfocus.com/bid/9699
http://www.cisco.com/warp/public/707/cisco-sa-20040219-ONS.shtml