Ubuntu Security Notice 473-1 – A buffer overflow was discovered in libgd2’s font renderer. By tricking an application using libgd2 into rendering a specially crafted string with a JIS encoded font, a remote attacker could read heap memory or crash the application, leading to a denial of service. Xavier Roche discovered that libgd2 did not correctly validate PNG callback results. If an application were tricked into processing a specially crafted PNG image, it would monopolize CPU resources. Since libgd2 is often used in PHP and Perl web applications, this could lead to a remote denial of service.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/57152/USN-473-1.txt
Source: https://packetstormsecurity.com/files/57152/Ubuntu-Security-Notice-473-1.html