Instead, Facebook said, malicious browser extensions are to blame for monitoring the victims' activity and sending their messages and details to the hackers.
Five Russian Facebook users were contacted by BBC Russian Service since their private messages had been uploaded, BBC was able to confirm the posts belonged to them. But as you'd expect, there are also more sensitive discussions, including "intimate correspondence between two lovers", as the BBC describes it. The icon that gives access to the hackers to your account normally sits alongside your URL address bar waiting for you to click it. And this time, your personal messages on the platform are said to be targeted.
Facebook has not divulged the name of the extension it believes to be responsible for the data leak.
This revelation originally comes from the BBC Russian Service. It says that since Facebook is one of the biggest tech firms in the world and is already facing the heat for previous breaches, it is unlikely that the firm would've missed another large data breach.
All of the messages breached were of a personal nature, from the tame subject of dicussing a music concert to the more explicit.
A reply in English came from someone calling themself John Smith. On multiple occasions, it contacted local authorities to get the site brokering stolen information taken down. However, according to an outside expert reported by the BBC, it appears likely that at least 81,000 Facebook accounts had their privacy breached.