eCryptfs 104 and earlier uses a default salt to encrypt the mount passphrase, which makes it easier for attackers to obtain user passwords via a brute force attack.
http://www.ubuntu.com/usn/USN-2524-1
http://www.openwall.com/lists/oss-security/2015/02/28/3
http://www.openwall.com/lists/oss-security/2015/02/17/7
http://www.openwall.com/lists/oss-security/2015/02/10/16
http://lists.opensuse.org/opensuse-updates/2016-01/msg00118.html