Ubuntu Security Notice 951-1 – Jun Mao discovered that Samba did not correctly validate SMB1 packet contents. An unauthenticated remote attacker could send specially crafted network traffic that could execute arbitrary code as the root user.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/90728/USN-951-1.txt
Source: https://packetstormsecurity.com/files/90728/Ubuntu-Security-Notice-951-1.html