Referenced CVEs: 
CVE-2007-2445
Description: 
=========================================================== Ubuntu Security Notice USN-472-1 June 11, 2007 libpng vulnerability CVE-2007-2445 =========================================================== A security issue affects the following Ubuntu releases: Ubuntu 6.06 LTS Ubuntu 6.10 Ubuntu 7.04 This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu. The problem can be corrected by upgrading your system to the following package versions: Ubuntu 6.06 LTS: libpng12-0 1.2.8rel-5ubuntu0.2 Ubuntu 6.10: libpng12-0 1.2.8rel-5.1ubuntu0.2 Ubuntu 7.04: libpng12-0 1.2.15~beta5-1ubuntu1 After a standard system upgrade you need to reboot your computer to effect the necessary changes. Details follow: It was discovered that libpng did not correctly handle corrupted CRC in grayscale PNG images. By tricking a user into opening a specially crafted PNG, a remote attacker could cause the application using libpng to crash, resulting in a denial of service.