It has come to my attention that a user has been trying to create an exploit through avatar image uploads. This was discovered when a user reported to me that they were getting a notice from their Norton Anti-virus saying "HTTP Suspicious Executable Image Download." This warning was referencing the user's avatar image. I don't think they had actually achieved anything in the way of stealing information or anything like that, but I assume it could be possible if the hole is left open long enough. I use PHP to upload the image files, and I check if the file being uploaded is a png, jpg, or gif.