Cisco IOS 12.0S, 12.2, and 12.3, with Open Shortest Path First (OSPF) enabled, allows remote attackers to cause a denial of service (device reload) via a malformed OSPF packet.
Cisco IOS 12.2(15) and earlier allows remote attackers to cause a denial of service (refused VTY (virtual terminal) connections), via a crafted TCP connection to the Telnet or reverse Telnet port.