A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco IOS 15.0 through 15.6 and Cisco IOS XE 3.5 through 16.5 could allow an unauthenticated, remote attacker to cause high CPU utilization, traceback messages, or a reload of an affected device that leads to a denial of service (DoS) condition. The vulnerability is due to how an affected device processes certain IKEv2 packets. An attacker could exploit this vulnerability by sending specific IKEv2 packets to an affected device to be processed. A successful exploit could allow the attacker to cause high CPU utilization, traceback messages, or a reload of the affected device that leads to a DoS condition. This vulnerability affects Cisco devices that have the Internet Security Association and Key Management Protocol (ISAKMP) enabled. Although only IKEv2 packets can be used to trigger this vulnerability, devices that are running Cisco IOS Software or Cisco IOS XE Software are vulnerable when ISAKMP is enabled. A device does not need to be configured with any IKEv2-specific features to be vulnerable. Many features use IKEv2, including different types of VPNs such as the following: LAN-to-LAN VPN; Remote-access VPN, excluding SSL VPN; Dynamic Multipoint VPN (DMVPN); and FlexVPN. Cisco Bug IDs: CSCvc41277.

A vulnerability in the Cisco Network Plug and Play application of Cisco IOS 12.4 through 15.6 and Cisco IOS XE 3.3 through 16.4 could allow an unauthenticated, remote attacker to gain unauthorized access to sensitive data by using an invalid certificate. The vulnerability is due to insufficient certificate validation by the affected software. An attacker could exploit this vulnerability by supplying a crafted certificate to an affected device. A successful exploit could allow the attacker to conduct man-in-the-middle attacks to decrypt confidential information on user connections to the affected software. Cisco Bug IDs: CSCvc33171.

The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.2 through 3.17 contains multiple vulnerabilities that could allow an authenticated, remote attacker to remotely execute code on an affected system or cause an affected system to reload. An attacker could exploit these vulnerabilities by sending a crafted SNMP packet to an affected system via IPv4 or IPv6. Only traffic directed to an affected system can be used to exploit these vulnerabilities. The vulnerabilities are due to a buffer overflow condition in the SNMP subsystem of the affected software. The vulnerabilities affect all versions of SNMP: Versions 1, 2c, and 3. To exploit these vulnerabilities via SNMP Version 2c or earlier, the attacker must know the SNMP read-only community string for the affected system. To exploit these vulnerabilities via SNMP Version 3, the attacker must have user credentials for the affected system. All devices that have enabled SNMP and have not explicitly excluded the affected MIBs or OIDs should be considered vulnerable. Cisco Bug IDs: CSCve60376, CSCve78027.

A vulnerability in a startup script of Cisco IOS XE Software could allow an unauthenticated attacker with physical access to the targeted system to execute arbitrary commands on the underlying operating system with the privileges of the root user. More Information: CSCuz06639 CSCuz42122. Known Affected Releases: 15.6(1.1)S 16.1.2 16.2.0 15.2(1)E. Known Fixed Releases: Denali-16.1.3 16.2(1.8) 16.1(2.61) 15.6(2)SP 15.6(2)S1 15.6(1)S2 15.5(3)S3a 15.5(3)S3 15.5(2)S4 15.5(1)S4 15.4(3)S6a 15.4(3)S6 15.3(3)S8a 15.3(3)S8 15.2(5)E 15.2(4)E3 15.2(3)E5 15.0(2)SQD3 15.0(1.9.2)SQD3 3.9(0)E.

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 web user interface of Cisco IOS XE 3.1 through 3.17 could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to insufficient resource handling by the affected software when the web user interface is under a high load. An attacker could exploit this vulnerability by sending a high number of requests to the web user interface of the affected software. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. To exploit this vulnerability, the attacker must have access to the management interface of the affected software, which is typically connected to a restricted management network. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS XE Software, if the web user interface of the software is enabled. By default, the web user interface is not enabled. Cisco Bug IDs: CSCup70353.

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.

The Neighbor Discovery (ND) protocol implementation in the IPv6 stack in Cisco IOS XE 2.1 through 3.17S, IOS XR 2.0.0 through 5.3.2, and NX-OS allows remote attackers to cause a denial of service (packet-processing outage) via crafted ND messages, aka Bug ID CSCuz66542, as exploited in the wild in May 2016.

The NTP implementation in Cisco IOS 15.1 and 15.5 and IOS XE 3.2 through 3.17 allows remote attackers to modify the system time via crafted packets, aka Bug ID CSCux46898.

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.

Cisco IOS XE 3.5E and earlier on WS-C3850, WS-C3860, and AIR-CT5760 devices does not properly parse the "request system shell" challenge response, which allows local users to obtain Linux root access by leveraging administrative privilege, aka Bug ID CSCur09815.

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.

Cisco IOS 12.0, 12.2, 12.4, 15.0, 15.1, 15.2, and 15.3 and IOS XE 2.x and 3.x before 3.7.4S; 3.2.xSE and 3.3.xSE before 3.3.2SE; 3.3.xSG and 3.4.xSG before 3.4.4SG; and 3.8.xS, 3.9.xS, and 3.10.xS before 3.10.1S allow remote attackers to cause a denial of service (device reload) via malformed RSVP packets, aka Bug ID CSCui11547.

The EnergyWise module in Cisco IOS 12.2, 15.0, 15.1, 15.2, and 15.4 and IOS XE 3.2.xXO, 3.3.xSG, 3.4.xSG, and 3.5.xE before 3.5.3E allows remote attackers to cause a denial of service (device reload) via a crafted IPv4 packet, aka Bug ID CSCup52101.

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 12.2 and 15.0 through 15.3 and IOS XE 3.2 through 3.7 before 3.7.5S and 3.8 through 3.10 before 3.10.1S allow remote attackers to cause a denial of service (device reload) via a malformed IKEv2 packet, aka Bug ID CSCui88426.