ZdNet: First it was PNG, Now its JPEG !

The critical flaw has to do with how Microsoft's operating systems and other software process the widely used JPEG image format and could let attackers create an image file that would run a malicious program on a victim's computer as soon as the file is viewed.

A sample program hit the Internet, showing by example how malicious coders could compromise Windows computers by using a flaw in the handling of a widespread graphics format by Microsoft's software. More on this, here.