Remote exploitation of a buffer overflow in the Mozilla Foundation’s libpr0n image processing library allows attackers to execute arbitrary code. The libpr0n GIF parser was designed using a state machine which is represented as a series of switch/case statements. One particularly interesting state, ‘gif_image_header’, is responsible for interpreting a single image/frame description record. A single GIF file may contain many images, each with a different color map associated. The problem lies in the handling of changes to the color map of subsequent images in a multiple-image GIF file. Memory reallocation is not managed correctly and can result in an exploitable heap overflow condition. iDefense confirmed the existence of this vulnerability using Mozilla Firefox versions 3.0.13 and 3.5.2 on 32-bit Windows XP SP3. Other versions, and potentially other applications using libpr0n, are suspected to be vulnerable.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/82320/10.28.09-1.txt
Source: https://packetstormsecurity.com/files/82320/iDEFENSE-Security-Advisory-2009-10-28.1.html