Cisco IOS 12.4 and earlier, when using the crypto packages and SSL support is enabled, allows remote attackers to cause a denial of service via a malformed (1) ClientHello, (2) ChangeCipherSpec, or (3) Finished message during an SSL session.

The Cisco Intrusion Prevention System (IPS) and IOS with Firewall/IPS Feature Set do not properly handle certain full-width and half-width Unicode character encodings, which might allow remote attackers to evade detection of HTTP traffic.

The FTP Server in Cisco IOS 11.3 through 12.4 does not properly check user authorization, which allows remote attackers to execute arbitrary code, and have other impact including reading startup-config, as demonstrated by a crafted MKD command that involves access to a VTY device and overflows a buffer, aka bug ID CSCek55259.

Cisco IOS 9.x, 10.x, 11.x, and 12.x and IOS XR 2.0.x, 3.0.x, and 3.2.x allows remote attackers to cause a denial of service or execute arbitrary code via a crafted IP option in the IP header in a (1) ICMP, (2) PIMv2, (3) PGM, or (4) URD packet.

Memory leak in the TCP listener in Cisco IOS 9.x, 10.x, 11.x, and 12.x allows remote attackers to cause a denial of service by sending crafted TCP traffic to an IPv4 address on the IOS device.

Cisco IOS allows remote attackers to cause a denial of service (crash) via a crafted IPv6 Type 0 Routing header.

The VLAN Trunking Protocol (VTP) feature in Cisco IOS 12.1(19) and CatOS allows remote attackers to cause a denial of service by sending a VTP update with a revision value of 0x7FFFFFFF, which is incremented to 0x80000000 and is interpreted as a negative number in a signed context.

Heap-based buffer overflow in the VLAN Trunking Protocol (VTP) feature in Cisco IOS 12.1(19) allows remote attackers to execute arbitrary code via a long VLAN name in a VTP type 2 summary advertisement.

The VLAN Trunking Protocol (VTP) feature in Cisco IOS 12.1(19) allows remote attackers to cause a denial of service by sending a VTP version 1 summary frame with a VTP version field value of 2.

Cisco IOS 12.0, 12.1, and 12.2, when GRE IP tunneling is used and the RFC2784 compliance fixes are missing, does not verify the offset field of a GRE packet during decapsulation, which leads to an integer overflow that references data from incorrect memory locations, which allows remote attackers to inject crafted packets into the routing queue, possibly bypassing intended router ACLs.