Ubuntu Security Notice USN-785-1 – It was discovered that ipsec-tools did not properly handle certain fragmented packets. A remote attacker could send specially crafted packets to the server and cause a denial of service. It was discovered that ipsec-tools did not properly handle memory usage when verifying certificate signatures or processing nat-traversal keep-alive messages. A remote attacker could send specially crafted packets to the server and exhaust available memory, leading to a denial of service.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/78176/USN-785-1.txt
Source: https://packetstormsecurity.com/files/78176/Ubuntu-Security-Notice-785-1.html