Ubuntu Security Notice 996-1 – It was discovered that Mako incorrectly filtered single-quote characters when performing html filtering. An attacker could utilize this to perform cross-site scripting attacks.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/94352/USN-996-1.txt
Source: https://packetstormsecurity.com/files/94352/Ubuntu-Security-Notice-996-1.html