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More than 412 million user accounts have reportedly been exposed in a massive data breach of adult dating and entertainment company FriendFinder Networks.

The hack included email addresses and passwords collected over 20 years from six adult-oriented FriendFinder websites, including Penthouse.com, according to LeakedSource, which disclosed the breach Sunday. The data breach monitoring service said bulk of the accounts exposed -- more than 339 million -- came from AdultFriendFinder.com, which the company describes as the "world's largest sex and swinger community."

The hack is believed to have occurred in October and included information from more than 15 million accounts LeakedSource believes were deleted by their users but the information was still saved on the network.

FriendFinder could not be reached for comment but confirmed the site vulnerability to CNET sister site ZDNet.

"Over the past several weeks, FriendFinder has received a number of reports regarding potential security vulnerabilities from a variety of sources," Diana Ballou, FriendFinder vice president and senior counsel, told ZDNet. "While a number of these claims proved to be false extortion attempts, we did identify and fix a vulnerability that was related to the ability to access source code through an injection vulnerability."

The hack marks the second time in two years that AdultFriendFinder has been hacked, according to LeakedSource. The site, which matches people for sexual encounters, was hacked in May 2015, exposing more than 3.5 million accounts.