Adding a user to the "docker" group will grant the ability to run containers which can be used to obtain root privileges on the docker host. code example
Example 1: docker post installation steps linux
sudo groupadd docker
sudo usermod -aG docker $USER
gnome-session-quit
Example 2: docker sudo how to add user
FROM alpine:latest
RUN apk --no-cache update \
&& apk --no-cache add sudo
copy run.sh /usr/local/
RUN addgroup -S cassandra && adduser -S cassandra -G cassandra
RUN chown -R cassandra:cassandra /home/cassandra/
RUN echo 'cassandra ALL=(ALL) /bin/su' >> /etc/sudoers
USER cassandra
ENTRYPOINT [ "sh","/usr/local/run.sh"]