Ubuntu Security Notice 556-1 – Alin Rad Pop discovered that Samba did not correctly check the size of reply packets to mailslot requests. If a server was configured with domain logon enabled, an unauthenticated remote attacker could send a specially crafted domain logon packet and execute arbitrary code or crash the Samba service. By default, domain logon is disabled in Ubuntu.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/61920/USN-556-1.txt
Source: https://packetstormsecurity.com/files/61920/Ubuntu-Security-Notice-556-1.html