Vulnerabilities in Rancher Server and Agent Images

A recent scan on rancher server and agent images resulted in hundreds of vulnerabilities, basically related to ubuntu base image(16.04,14.04). I am aware that rancher 1.6 is already EOM and no more images will be build further unless there is a critical security issue. However, is there any possibility to build local images(using Dockerfile with latest ubuntu base image) from our side till Rancher 1.6 EOL deadline? I have explored some Dockerfiles in the rancher github repository(agent/server-base and other infra containers), but those appears to be incomplete. Would anyone kindly guide to the latest dockerfiles which we can use to build rancher server, agent and basic infra containers(net, dns, scheduler, secrets, metadata, ipsec) etc?

I managed to make a rancher-server 1.6.29 container based on Ubuntu 18.04: