Multiple memory leaks in Cisco IOS 12.0 through 12.4 allow remote attackers to cause a denial of service (device crash) via a malformed SIP packet, aka (1) CSCsf11855, (2) CSCeb21064, (3) CSCse40276, (4) CSCse68355, (5) CSCsf30058, (6) CSCsb24007, and (7) CSCsc60249.

Cisco IOS 12.0 through 12.4 allows remote attackers to cause a denial of service (device crash) via (1) "abnormal" MGCP messages, aka CSCsd81407; and (2) a large facsimile packet, aka CSCej20505.

Unspecified vulnerability in Cisco IOS and Cisco IOS XR 12.x up to 12.3, including some versions before 12.3(15) and 12.3(14)T, allows remote attackers to obtain sensitive information (partial packet contents) or cause a denial of service (router or component crash) via crafted IPv6 packets with a Type 0 routing header.

Cisco IOS 12.0 through 12.4 allows remote attackers to cause a denial of service via (1) a malformed MGCP packet, which causes a device hang, aka CSCsf08998; a malformed H.323 packet, which causes a device crash, as identified by (2) CSCsi60004 with Proxy Unregistration and (3) CSCsg70474; and a malformed Real-time Transport Protocol (RTP) packet, which causes a device crash, as identified by (4) CSCse68138, related to VOIP RTP Lib, and (5) CSCse05642, related to I/O memory corruption.

Unspecified vulnerability in Cisco IOS 12.0 through 12.4 allows remote attackers to execute arbitrary code via a malformed SIP packet, aka CSCsi80749.

Buffer overflow in the Next Hop Resolution Protocol (NHRP) functionality in Cisco IOS 12.0 through 12.4 allows remote attackers to cause a denial of service (restart) and execute arbitrary code via a crafted NHRP packet.

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 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.

The Intrusion Prevention System (IPS) feature for Cisco IOS 12.4XE to 12.3T allows remote attackers to bypass IPS signatures that use regular expressions via fragmented packets.

The ATOMIC.TCP signature engine in the Intrusion Prevention System (IPS) feature for Cisco IOS 12.4XA, 12.3YA, 12.3T, and other trains allows remote attackers to cause a denial of service (IPS crash and traffic loss) via unspecified manipulations that are not properly handled by the regular expression feature, as demonstrated using the 3123.0 (Netbus Pro Traffic) signature.