nbd-server in Network Block Device (nbd) before 3.5 does not properly check IP addresses, which might allow remote attackers to bypass intended access restrictions via an IP address that has a partial match in the authfile configuration file.
http://www.ubuntu.com/usn/USN-2676-1
http://www.securityfocus.com/bid/64002
http://www.openwall.com/lists/oss-security/2013/11/29/4