Cisco Security Advisory – A vulnerability within the virtual routing and forwarding (VRF) subsystem of Cisco IOS software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to a failure to properly process malicious ICMP version 4 (ICMPv4) messages received on a VRF-enabled interface. An attacker could exploit this vulnerability by submitting ICMPv4 messages designed to trigger the vulnerability on an affected device. When the ICMPv4 messages are processed, the packet queue of the affected interface may not be cleared, leading to a queue wedge. When a wedge occurs, the affected device will stop processing any additional packets received on the wedged interface. Cisco has released free software updates that address this vulnerability. Workarounds that mitigate this vulnerability are not available.