Docker Engine before 1.6.1 uses weak permissions for (1) /proc/asound, (2) /proc/timerstats, (3) /proc/latencystats, and (4) /proc/fs, which allows local users to modify the host, obtain sensitive information, and perform protocol downgrade attacks via a crafted image.
Libcontainer and Docker Engine before 1.6.1 opens the file-descriptor passed to the pid-1 process before performing the chroot, which allows local users to gain privileges via a symlink attack in an image.
Docker Engine before 1.6.1 allows local users to set arbitrary Linux Security Modules (LSM) and dockert policies via an image that allows volumes to override files in /proc.