I am assuming this is a fake but a check of the usual fake nude sites does not show this particular picture. If it is a fake, and I am sure it must be, it is a very good one. I know a thing or two about photo editing and I cannot see the seams in this. The proportions look correct and the hair, which is the hardest part to join in without just having it blur in, seems perfect.
Maybe Summer has an identical twin sister and this is her?