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.
The on-line help system options in Cisco routers allows non-privileged users without "enabled" access to obtain sensitive information via the show command.
The IOS HTTP service in Cisco routers and switches running IOS 11.1 through 12.1 allows remote attackers to cause a denial of service by requesting a URL that contains a %% string.
Cisco IOS 11.x and 12.x allows remote attackers to cause a denial of service by sending the ENVIRON option to the Telnet daemon before it is ready to accept it, which causes the system to reboot.