The issue began with users in France, which is the latest country to be switched over to the Timeline layout. The French newspaper Metro first reported complaints when users found old private material posted on public timelines.
"A small number of users raised concerns after what they believed to be private messages appeared on their timeline,” Facebook said in a widely-reported statement. “Our engineers investigated these reports and found that the messages were older wall posts that had always been visible on the users' profile pages. Facebook is satisfied that there has been no breach of user privacy."
Meanwhile a Facebook spokesperson told the BBC that inadvertent publishing of private messages is actually technically impossible. There is "no mechanism" that has ever been created that would allow a those two silos of information to mingle, the source said.
Users took to Twitter to express opposing viewpoints. As just one example, former CBC employee Kim Fox told CBC that she found several private Facebook messages from 2008 to 2012 posted on her timeline. Fox said she also saw private messages written by her on friends' pages.
The issue is likely a function of users forgetting how friends interacted with each other on the friend feed in previous versions of the Facebook interface. Wall posts functioned more like messaging.
Just to be sure, an Infosecurity staffer offers this fix: Within Timeline, click on the year on the right side of the screen (2007, 2008, 2009), and a box will appear with friends' messages and a header that says “[X number of] people have written on [user’s] timeline.” Hover over the right side until the pencil icon appears, click on it and select “hide from timeline”. Do this for each year.