A vulnerability in the Layer 2 Tunneling Protocol (L2TP) parsing function of Cisco IOS (12.0 through 12.4 and 15.0 through 15.6) and Cisco IOS XE (3.1 through 3.18) could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to insufficient validation of L2TP packets. An attacker could exploit this vulnerability by sending a crafted L2TP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS or Cisco IOS XE Software if the L2TP feature is enabled for the device and the device is configured as an L2TP Version 2 (L2TPv2) or L2TP Version 3 (L2TPv3) endpoint. By default, the L2TP feature is not enabled. Cisco Bug IDs: CSCuy82078.

A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges. The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between cluster members. The vulnerability is due to the combination of two factors: (1) the failure to restrict the use of CMP-specific Telnet options only to internal, local communications between cluster members and instead accept and process such options over any Telnet connection to an affected device; and (2) the incorrect processing of malformed CMP-specific Telnet options. An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device. This affects Catalyst switches, Embedded Service 2020 switches, Enhanced Layer 2 EtherSwitch Service Module, Enhanced Layer 2/3 EtherSwitch Service Module, Gigabit Ethernet Switch Module (CGESM) for HP, IE Industrial Ethernet switches, ME 4924-10GE switch, RF Gateway 10, and SM-X Layer 2/3 EtherSwitch Service Module. Cisco Bug IDs: CSCvd48893.

The AAA service in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.1 through 3.18 and 16.2 allows remote attackers to cause a denial of service (device reload) via a failed SSH connection attempt that is mishandled during generation of an error-log message, aka Bug ID CSCuy87667.

Cisco IOS 12.2 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.17 and 16.2 allow remote attackers to cause a denial of service (device reload) via crafted fields in an H.323 message, aka Bug ID CSCux04257.

The Zone-Based Firewall (ZBFW) functionality in Cisco IOS, possibly 15.4 and earlier, and IOS XE, possibly 3.13 and earlier, mishandles zone checking for existing sessions, which allows remote attackers to bypass intended resource-access restrictions via spoofed traffic that matches one of these sessions, aka Bug IDs CSCun94946 and CSCun96847.

The server IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.6, IOS XE through 3.18S, IOS XR 4.3.x and 5.0.x through 5.2.x, and PIX before 7.0 allows remote attackers to obtain sensitive information from device memory via a Security Association (SA) negotiation request, aka Bug IDs CSCvb29204 and CSCvb36055 or BENIGNCERTAIN.

Cisco IOS XE 2.x and 3.x before 3.10.6S, 3.11.xS through 3.13.xS before 3.13.3S, and 3.14.xS through 3.15.xS before 3.15.1S allows remote attackers to cause a denial of service (device reload) via IPv4 packets that require NAT and MPLS actions, aka Bug ID CSCut96933.

Cisco IOS XE before 3.7.5S on ASR 1000 devices does not properly handle route adjacencies, which allows remote attackers to cause a denial of service (device hang) via crafted IP packets, aka Bug ID CSCub31873.

The Layer 4 Redirect (L4R) feature in Cisco IOS XE 2.x and 3.x before 3.10.4S, 3.11 before 3.11.3S, 3.12 before 3.12.2S, 3.13 before 3.13.1S, 3.14 before 3.14.0S, and 3.15 before 3.15.0S allows remote attackers to cause a denial of service (device reload) via malformed (1) IPv4 or (2) IPv6 packets, aka Bug ID CSCuq59131.

Cisco IOS 12.2, 12.4, 15.0, 15.1, 15.2, 15.3, and 15.4 and IOS XE 2.5.x, 2.6.x, 3.1.xS through 3.12.xS before 3.12.3S, 3.2.xE through 3.7.xE before 3.7.1E, 3.3.xSG, 3.4.xSG, and 3.13.xS before 3.13.2S allow remote attackers to cause a denial of service (memory consumption and device reload) by sending malformed IKEv2 packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCuo75572.

Cisco IOS 12.2, 12.4, 15.0, 15.1, 15.2, 15.3, and 15.4 and IOS XE 2.5.x, 2.6.x, 3.1.xS through 3.12.xS before 3.12.3S, 3.2.xE through 3.7.xE before 3.7.1E, 3.3.xSG, 3.4.xSG, and 3.13.xS before 3.13.2S allow remote attackers to cause a denial of service (device reload) by sending malformed IKEv2 packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCum36951.

Cisco IOS XE 2.x and 3.x before 3.9.0S, 3.10 before 3.10.0S, 3.11 before 3.11.0S, 3.12 before 3.12.0S, 3.13 before 3.13.0S, 3.14 before 3.14.0S, and 3.15 before 3.15.0S allows remote attackers to cause a denial of service (device reload) via crafted IPv6 packets, aka Bug ID CSCub68073.

The high-speed logging (HSL) feature in Cisco IOS XE 2.x and 3.x before 3.10.4S, 3.11 before 3.11.3S, 3.12 before 3.12.1S, 3.13 before 3.13.0S, 3.14 before 3.14.0S, and 3.15 before 3.15.0S allows remote attackers to cause a denial of service (device reload) via large IP packets that require NAT and HSL processing after fragmentation, aka Bug ID CSCuo25741.

The Common Flow Table (CFT) feature in Cisco IOS XE 3.6 and 3.7 before 3.7.1S, 3.8 before 3.8.0S, 3.9 before 3.9.0S, 3.10 before 3.10.0S, 3.11 before 3.11.0S, 3.12 before 3.12.0S, 3.13 before 3.13.0S, 3.14 before 3.14.0S, and 3.15 before 3.15.0S, when MMON or NBAR is enabled, allows remote attackers to cause a denial of service (device reload) via malformed IPv6 packets with IPv4 UDP encapsulation, aka Bug ID CSCua79665.

The Ethernet Connectivity Fault Management (CFM) handling feature in Cisco IOS 12.2(33)SRE9a and earlier and IOS XE 3.13S and earlier allows remote attackers to cause a denial of service (device reload) via malformed CFM packets, aka Bug ID CSCuq93406.

The L2TP module in Cisco IOS XE 3.10S(.2) and earlier on ASR 1000 routers allows remote authenticated users to cause a denial of service (ESP card reload) via a malformed L2TP packet, aka Bug ID CSCun09973.

Cisco ASR 1000 devices with software before 3.8S, when BDI routing is enabled, allow remote attackers to cause a denial of service (device reload) via crafted (1) broadcast or (2) multicast ICMP packets with fragmentation, aka Bug ID CSCub55948.

Cisco IOS XE 3.7S(.1) and earlier allows remote attackers to cause a denial of service (Packet Processor crash) via fragmented MPLS IP packets, aka Bug ID CSCul00709.

Cisco IOS XE 3.8S(.2) and earlier does not properly use a DHCP pool during assignment of an IP address, which allows remote authenticated users to cause a denial of service (device reload) via an AAA packet that triggers an address requirement, aka Bug ID CSCuh04949.