We've learned Woods has already unleashed attorney Michael Holtz, who's threatening to sue the site if it doesn't remove the Woods photo STAT.
Sources tell TMZ ... it wasn't Tiger's phone that was hacked, it was Vonn's. We're told Tiger had sent Vonn the naked pic while they were dating.
McPhee has also lawyered up and fired off a similar threatening letter. We're guessing the rest of the stars will follow suit.
There are huge stakes for whoever hacked the pics -- the guy responsible for "The Fappening" was sentenced to 18 months in federal prison.