MS04-028 disclosed a vulnerability in Windows JPEG processing. A specially-crafted JPEG image can produce a buffer overflow when displayed.
Why this matters
Images are everywhere. Web pages, email, documents, file shares — JPEGs are pervasive. A vulnerability that triggers on image display means almost every internet-connected user is potentially exposed.
What operators should do
Apply the patch. Update browsers. Update mail clients.
More as the situation develops.