Docker Engine before 1.6.1 uses weak permissions for (1) /proc/asound, (2) /proc/timer_stats, (3) /proc/latency_stats, and (4) /proc/fs, which allows local users to modify the host, obtain sensitive information, and perform protocol downgrade attacks via a crafted image.
https://groups.google.com/forum/#%21searchin/docker-user/1.6.1/docker-user/47GZrihtr-4/nwgeOOFLexIJ
http://www.securityfocus.com/bid/74566
http://seclists.org/fulldisclosure/2015/May/28
http://packetstormsecurity.com/files/131835/Docker-Privilege-Escalation-Information-Disclosure.html
http://lists.opensuse.org/opensuse-updates/2015-05/msg00023.html