Hayden Panettiere in "Room 23"
Here is a brightened version.
Some people claim this is Marisa Miller, but it could not be. The caption says it's an actress who is also elsewhere in the book clothed, but wanted to do an anonymous nude. Marisa Miller appears naked and fully identified elsewhere in the book. Hayden is an actress and appears elsewhere in the book clothed - with hair identical to the anonymous nude.
In addition, the photographer says that Hayden is naked in the book with her face hidden.