There is serious security exploit floating about the Internet concerning the parsing of image EXIF data by PHP driven webapps. The result can be a stack overflow, thus allowing abitrary code execution on some operating systems.
Look for CAN-2004-1065 at this link for more info:
However, PhotoPost users are immune from this security flaw because we do not
use PHP's exif extractor to obtain EXIF information from an image (its been unreliable for a long time).