Ubuntu Security Notice 491-1 – A flaw was discovered in Bind’s sequence number generator. A remote attacker could calculate future sequence numbers and send forged DNS query responses. This could lead to client connections being directed to attacker-controlled hosts, resulting in credential theft and other attacks.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/58053/USN-491-1.txt
Source: https://packetstormsecurity.com/files/58053/Ubuntu-Security-Notice-491-1.html