Thank you for pointing this out!

For those wanting to avoid upgrading to a new boot2docker release you can patch the vulnerability with the following command from the boot2docker shell:

  sudo sed -i "s/DOCKER_TLS:=''/DOCKER_TLS:=auto/g" /etc/init.d/docker && sudo /etc/init.d/docker restart

This will enable TLS by default and restart the docker daemon. Note that this will also kill all of your running containers.