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.

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.

Cisco ONS 15327 before 4.1(3), ONS 15454 before 4.6(1), ONS 15454 SD before 4.1(3), and Cisco ONS 15600 before 1.3(0) enable TFTP service on UDP port 69 by default, which allows remote attackers to GET or PUT ONS system files on the current active TCC in the /flash0 or /flash1 directories.

Cisco Internetwork Operating System (IOS) 12.0S through 12.3T attempts to process SNMP solicited operations on improper ports (UDP 162 and a randomly chosen UDP port), which allows remote attackers to cause a denial of service (device reload and memory corruption).