The design of the Hot Standby Routing Protocol (HSRP), as implemented on Cisco IOS 12.1, when using IRPAS, allows remote attackers to cause a denial of service (CPU consumption) via a router with the same IP address as the interface on which HSRP is running, which causes a loop.

The Cisco Optical Service Module (OSM) for the Catalyst 6500 and 7600 series running Cisco IOS 12.1(8)E through 12.1(13.4)E allows remote attackers to cause a denial of service (hang) via a malformed packet.

Cisco 2611 router running IOS 12.1(6.5), possibly an interim release, allows remote attackers to cause a denial of service via port scans such as (1) scanning all ports on a single host and (2) scanning a network of hosts for a single open port through the router. NOTE: the vendor could not reproduce this issue, saying that the original reporter was using an interim release of the software.

Cisco IOS 11.1 through 12.2, when HSRP support is not enabled, allows remote attackers to cause a denial of service (CPU consumption) via randomly sized UDP packets to the Hot Standby Routing Protocol (HSRP) port 1985.

Extended Interior Gateway Routing Protocol (EIGRP), as implemented in Cisco IOS 11.3 through 12.2 and other products, allows remote attackers to cause a denial of service (flood) by sending a large number of spoofed EIGRP neighbor announcements, which results in an ARP storm on the local network.

Multiple SSH2 servers and clients do not properly handle lists with empty elements or strings, which may allow remote attackers to cause a denial of service or possibly execute arbitrary code, as demonstrated by the SSHredder SSH protocol test suite.

Multiple SSH2 servers and clients do not properly handle strings with null characters in them when the string length is specified by a length field, which could allow remote attackers to cause a denial of service or possibly execute arbitrary code due to interactions with the use of null-terminated strings as implemented using languages such as C, as demonstrated by the SSHredder SSH protocol test suite.

Multiple SSH2 servers and clients do not properly handle large packets or large fields, which may allow remote attackers to cause a denial of service or possibly execute arbitrary code via buffer overflow attacks, as demonstrated by the SSHredder SSH protocol test suite.

Multiple SSH2 servers and clients do not properly handle packets or data elements with incorrect length specifiers, which may allow remote attackers to cause a denial of service or possibly execute arbitrary code, as demonstrated by the SSHredder SSH protocol test suite.

Cisco IOS 12.0 through 12.2, when supporting SSH, allows remote attackers to cause a denial of service (CPU consumption) via a large packet that was designed to exploit the SSH CRC32 attack detection overflow (CVE-2001-0144).