CVE 2013-4496
Samba 3.x before 3.6.23, 4.0.x before 4.0.16, and 4.1.x before 4.1.6 does not enforce the password-guessing protection mechanism for all interfaces, which makes it easier for remote attackers to obtain access via brute-force ChangePasswordUser2 (1) SAMR or (2) RAP attempts.
See the 
CVE page on Mitre.org
for more details.
