What is the right primer to use to cover wall paper in a bathroom?

If you dont remove the wallpaper, it can peel or show through the paint. :\

paintin g wallpaper is not a recommended practice, down the road regardless of a primer it will bubble and peel

Kilz

Especially in a bathroom you really should remove the wallpaper before painting. Even applying Kilz will not prevent moisture from getting behind the paper and bubbling. We made the mistake of painting over wallpaper, it then bubbled and pulled away from the wall. In our defense, we didn't know it was papered, as it had already been painted over, and who puts wallpaper on a backsplash area? Anyway, if you get a wallpaper shark and run it over the wallpaper, then spray with a 50/50 solution of fabric softener and water, it should scrape or peel off easily.

Diana is right on the money! All of that will happen as well as over time you'll see all the seams of the wallpaper surface. Plus unless this happens to be your forever home, you'll be passing on the same problem to the next person, adding a few more layers to its history:)