From TMZ:

Vanessa Hudgens is determined to teach a website an elementary lesson -- nude self portraits are meant for self, not others.
Vanessa is suing the owners, claiming the website posted and refused to take down nude, "self portrait photographs" taken in a private home. The photos were taken on a cell phone. The suit doesn't mention the photos show Vanessa naked, but the pics on the site tell the story.
As for how the photos got out, the lawsuit explains, "The photos were obtained by unknown methods and posted on the internet by an unknown person without Hudgens' knowledge or consent.
"Interestingly, Vanessa registered the nude photos with the U.S. Copyright Office.
Vanessa's lawyers cried copyright violation but Butter Media, the company that owns the website, was unmoved.
So Vanessa has filed a federal lawsuit and is asking the judge for an injunction, ordering the site to take the photos down. She also wants damages.