The do_remount function in fs/namespace.c in the Linux kernel through 3.16.1 does not maintain the MNT_LOCK_READONLY bit across a remount of a bind mount, which allows local users to bypass an intended read-only restriction and defeat certain sandbox protection mechanisms via a mount -o remount command within a user namespace. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-5206
