The mozilla applications contain several image decoders for displaying images of various formats. Amoung the most common image formats is the Graphic Information File (GIF) format. The code for this parser is located in: mozilla/modules/libpr0n/decoders/gif/GIF2.cpp A vulnerability exists in the parsing of a Netscape-specific extension block that specifies a 32-bit size integer indicating how much image data the application should buffer, which is shown (taken from the gif_write() function).
Lifting embargo
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2005-336.html