Cisco Security Advisory – A vulnerability in the processing of IPv4 packets that require Network Address Translation (NAT) and Multiprotocol Label Switching (MPLS) services of Cisco IOS XE Software for Cisco ASR 1000 Series, Cisco ISR 4300 Series, Cisco ISR 4400 Series, and Cisco Cloud Services 1000v Series Routers could allow an unauthenticated, remote attacker to cause a reload of the affected device. The vulnerability is due to improper processing of IPv4 packets that require NAT and MPLS processing. An attacker could exploit this vulnerability by sending an IPv4 packet to be processed by a Cisco IOS XE device configured to perform NAT and MPLS services. A successful exploit could allow the attacker to cause a reload of the affected device. Cisco has released software updates that address these vulnerabilities. There are no workarounds to mitigate this vulnerability.