Sounds like former child star Jesse McCartney made his ex angry enough that she wants to get revenge by distributing a naughty nude photo of the star!

The NY Post received a photo of a nearly nude Jesse McCartney -- that allegedly came from his ex -- lying on a bed, completely naked except for a G-string made out of candy!

The Take Your Sweet Time singer has already sicced his lawyers on the matter, sending X17online a legal notice that reads, "Mr. McCartney did not knowingly participate in the taking of this photo and did not consent to the taking of such a photo. In addition, the alleged photo of Mr. McCartney appears to have been manipulated and doctored by computer software."