Rihanna Nude Pictures Leak Celeb Hackers Up the Ante

The celebrity hackers are back ... with a vengeance.  The latest victim appears to be Rihanna -- despite the fact that a simple Google search reveals her boobs line the online landscape.

Early Sunday AM two nude pictures that appear to be RiRi were leaked onto 4chan/Reddit ... one with a censored version of her breasts ... the other pic showing bare ass and slight nipple.

They look like they were taken during some sort of fitting.

As we previously reported ... a second wave of leaks has been going down all weekend -- nude pics of what appears to be Kim Kardashian, Vanessa Hudgens, Kate Bosworth and Hope Solo have all surfaced.

Gabrielle Union is also a victim -- topless pictures of her surfaced -- and she told us her legal team will contact the FBI.

We reached out to Rihanna's rep -- so far, no word back.