Cisco Security Advisory – Devices running Cisco IOS Software or IOS XE Software contain vulnerabilities within the Internet Key Exchange (IKE) version 2 subsystem that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerabilities are due to how an affected device processes certain malformed IKEv2 packets. An attacker could exploit these vulnerabilities by sending malformed IKEv2 packets to an affected device to be processed. A successful exploit could allow the attacker to cause a reload of the affected device or excessive consumption of resources that would lead to a DoS condition. IKEv2 is automatically enabled on devices running Cisco IOS and Cisco IOS XE Software when the Internet Security Association and Key Management Protocol (ISAKMP) is enabled. These vulnerabilities can be triggered only by sending malformed IKEv2 packets. There are no workarounds for the vulnerabilities described in this advisory. Cisco has released free software updates that address these vulnerabilities.