The point of messaging app Snapchat is that photos, once sent, are supposed to disappear. But thousands reappeared Thursday night when hackers posted a database of purported stolen Snapchat photos and videos on the notorious 4Chan message boards, the same place where hackers leaked stolen iPhone photos of nude celebrities this past summer.

Snapchat told International Business Times on Friday that it had confirmed its servers were not breached, and said it was not the source of the leaks. Blogger Kenny Withers, who was first to report the Snapchat leaks, said that third-party apps like Snap Save enabled hackers to store hundreds of thousands of the nude “selfies.”

“Snapchatters were allegedly victimized by their use of third-party apps to send and receive Snaps, a practice that we expressly prohibit in our Terms of Use precisely because they compromise our users’ security,” Snapchat said in a statement. “We vigilantly monitor the App Store and Google Play for illegal third-party apps and have succeeded in getting many of these removed.”

The Snap Save app was pulled from the Apple Store months ago, but another, called Snapsave, remains available online for Google’s Android phones. It was not immediately clear whether hackers had gotten access to the app’s servers, where 13 gigabytes of Snapchat photos were stored, or whether they had been collecting the files over a long period of time.

Snapsave allows users to keep Snapchat photos and videos, which are made to automatically delete after they are viewed through the official app. Some 4chan users called the stolen photo release “The Snappening" and noted it was on a much larger scale than the widely reported hacks that targeted celebrities’ iCloud accounts in August.

The user community on Reddit, however, was much less convinced. Users on that site said that Withers’ report was false. Others noted that some of the photos had been “floating around for ages” and inferred the blogger might be trying to make a name for himself.

Other 4chan users claim the culprit was not a mobile app but rather, a former Web app that allowed Snapchat users to receive and save “snaps.” They also said that many of the images were of young children under the legal age of consent and therefore also constituted child pornography. According to Digiday, 50 percent of Snapchat users are aged 13 to 17.

One commenter on Withers’ site claimed s/he was behind both the celebrity nude photo scandal and the recent release of Snapchat images. The commenter threatened to release even more stolen images on Sunday. “I was the person behind both the fappening and the snappening. I am going to start a thread on October 12th at 2:16 PM where I am going to be releasing even more nudes.”

Update (2:20 p.m. EDT): Snapsave developer Georgie Casey told Engadget his app "had nothing to do with it and we've never logged username/passwords." He also said that Snapsave did not run on the cloud, and therefore would not have stored user photos in a way that made them broadly accessible to hackers.