Ubuntu Security Notice 640-1 – Andreas Solberg discovered that libxml2 did not handle recursive entities safely. If an application linked against libxml2 were made to process a specially crafted XML document, a remote attacker could exhaust the system’s CPU resources, leading to a denial of service.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/69621/USN-640-1.txt
Source: https://packetstormsecurity.com/files/69621/Ubuntu-Security-Notice-640-1.html