CVE-2017-12150
It was found that samba before 4.4.16, 4.5.x before 4.5.14, and 4.6.x before 4.6.8 did not enforce "SMB signing" when certain configuration options were enabled. A remote attacker could launch a man-in-the-middle attack and retrieve information in plain-text.
Source: CVE-2017-12150