Ubuntu Security Notice USN-725-1 – It was discovered that Kmail did not adequately prevent execution of arbitrary code when a user clicked on a URL to an executable within an HTML mail. If a user clicked on a malicious URL and chose to execute the file, a remote attacker could execute arbitrary code with user privileges. This update changes KMail’s behavior to instead launch a helper program to view the file if the user chooses to execute such a link.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/75261/USN-725-1.txt
Source: https://packetstormsecurity.com/files/75261/Ubuntu-Security-Notice-725-1.html