Ubuntu Security Notice USN-717-2 – A flaw was discovered in the browser engine when restoring closed tabs. If a user were tricked into restoring a tab to a malicious website with form input controls, an attacker could steal local files on the user’s system. Wladimir Palant discovered that Firefox did not restrict access to cookies in HTTP response headers. If a user were tricked into opening a malicious web page, a remote attacker could view sensitive information.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/74864/USN-717-2.txt
Source: https://packetstormsecurity.com/files/74864/Ubuntu-Security-Notice-717-2.html