It was an accident. Yeah. That’s the ticket.
The Facebook app was caught activating the camera on iPhones while users were scrolling through their newsfeed. This was originally discovered by Joshua Maddux of 95Visual, a web design firm. He had initially believed he had opened the camera on accident, but found that it had happened more than once, and eventually posted a video of it happening on Twitter.
A security engineer by the name of Jerry Gamblin from Kenna Security was able to reproduce the issue, but does not believe the video taken by the camera was being uploaded to Facebook.
Facebook states that they have submitted an update to the Apple App Store that will resolve the issue.
The issue did not affect Android devices. As with every Apple issue, the recommendation is to turn something off. In this case, it is to revoke access to the camera from the Facebook App.