Buffer overflow in Cisco IOS 11.2.x to 12.0.x allows remote attackers to cause a denial of service and possibly execute commands via a large number of OSPF neighbor announcements.
Cisco devices IOS 12.0 and earlier allow a remote attacker to cause a crash, or bad route updates, via malformed BGP updates with unrecognized transitive attribute.
Cisco switches and routers running IOS 12.1 and earlier produce predictable TCP Initial Sequence Numbers (ISNs), which allows remote attackers to spoof or hijack TCP connections.
Vulnerability in Cisco IOS 11.1 through 11.3 with distributed fast switching (DFS) enabled allows remote attackers to bypass certain access control lists when the router switches traffic from a DFS-enabled input interface to an output interface with a logical subinterface, as described by Cisco bug CSCdk43862.