Cisco IOS 12.1\(20\)e

The DNS forwarder in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.15 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (data corruption or device reload) via a crafted DNS response, aka Bug ID CSCup90532.

Secure Shell (SSH) 2 in Cisco IOS 12.0 through 12.3 allows remote attackers to cause a denial of service (device reload) (1) via a username that contains a domain name when using a TACACS+ server to authenticate, (2) when a new SSH session is in the login phase and a currently logged in user issues a send command, or (3) when IOS is logging messages and an SSH session is terminated while the server is sending data.

Cisco IOS and IOS XE Software VLAN Trunking Protocol Denial of Service Vulnerability

Cisco IOS 12.0(5)XU through 12.1(2) allows remote attackers to read system administration and topology information via an "snmp-server host" command, which creates a readable "community" community string if one has not been previously created.

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).