In theory, if you don’t apply the latest MS security patch, your system could be compromised by a buffer overrun if you download the wrong JPEG file.
Vmyths.com has this to say:“On 14 September 2004, Microsoft issued a “critical” alert regarding a “buffer overrun” in software it uses to display JPEG images. In theory, if you try to view a specially crafted JPEG file, it could take over your computer and do whatever it wishes. Microsoft has released a security patch to fix this buffer overrun. Vmyths urges you to download the patch, install it, and get on with your life.”