Ubuntu Security Notice 918-1 – It was discovered the Samba handled symlinks in an unexpected way when both “wide links” and “UNIX extensions” were enabled, which is the default. A remote attacker could create symlinks and access arbitrary files from the server.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/87591/USN-918-1.txt
Source: https://packetstormsecurity.com/files/87591/Ubuntu-Security-Notice-918-1.html