Unknown vulnerability in Cisco ONS 15327 before 4.1(3), ONS 15454 before 4.6(1), ONS 15454 SD before 4.1(3), and Cisco ONS15600 before 1.3(0) allows a superuser whose account is locked out, disabled, or suspended to gain unauthorized access via a Telnet connection to the VxWorks shell.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15266
http://www.securityfocus.com/bid/9699
http://www.cisco.com/warp/public/707/cisco-sa-20040219-ONS.shtml