A vulnerability in the Tool Command Language (Tcl) interpreter of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, local attacker with privileged EXEC credentials to cause a denial of service (DoS) condition on an affected system. The vulnerability is due to insufficient input validation of data passed to the Tcl interpreter. An attacker could exploit this vulnerability by executing crafted Tcl arguments on an affected device. An exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

A vulnerability in the Hot Standby Router Protocol (HSRP) subsystem of Cisco IOS and IOS XE Software could allow an unauthenticated, adjacent attacker to receive potentially sensitive information from an affected device. The vulnerability is due to insufficient memory initialization. An attacker could exploit this vulnerability by receiving HSRPv2 traffic from an adjacent HSRP member. A successful exploit could allow the attacker to receive potentially sensitive information from the adjacent device.

The DNS forwarder in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.15 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (data corruption or device reload) via a crafted DNS response, aka Bug ID CSCup90532.

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.

Cisco IOS XR through 5.3.2 mishandles Local Packet Transport Services (LPTS) flow-base entries, which allows remote attackers to cause a denial of service (session drop) by making many connection attempts to open TCP ports, aka Bug ID CSCux95576.

Cisco IOS XR 3.8.1 and earlier allows remote authenticated users to cause a denial of service (process crash) via vectors involving a BGP UPDATE message with many AS numbers prepended to the AS path.

Cisco IOS XR, when configured for Multi Protocol Label Switching (MPLS) and running on Cisco CRS-1 or Cisco 12000 series routers, allows remote attackers to cause a denial of service (Line card crash) via certain MPLS packets, as identified by Cisco bug ID CSCsc77475.

Cisco IOS XR, when configured for Multi Protocol Label Switching (MPLS) and running on Cisco CRS-1 routers, allows remote attackers to cause a denial of service (Modular Services Cards (MSC) crash or "MPLS packet handling problems") via certain MPLS packets, as identified by Cisco bug IDs (1) CSCsd15970 and (2) CSCsd55531.