If your IPv6 strategy is to delay implementation as long as you can, you still must address IPv6 security concerns. The biggest looming security threat lies in the fact that enterprise networks already have tons of IPv6 enabled devices. Stateless auto-configuration allows any IPv6-enabled device to communicate with other IPv6 network devices and services on the same LAN. Cisco and the IETF are in the process of implementing the same security mechanisms for IPv6 that are currently used to protect IPv4.”]
Source: https://www.csoonline.com/article/2130207/hackers-target-ipv6.html