A vulnerability in the IPv6 processing code of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload. The vulnerability is due to incorrect handling of specific IPv6 hop-by-hop options. An attacker could exploit this vulnerability by sending a malicious IPv6 packet to or through the affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition on an affected device.
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180926-ipv6hbh