This is a very odd bug. Are there any other details you can provide, like your control scheme or operating system? I've never encountered anything like this or had this reported before so I'll need more info to try and replicate it.
In the meantime perhaps try switching from what you're using to an alternative (etc if using KBM try Gamepad) and seeing if it continues to occur. I can say there's nothing in the backend that causes forced continual movement outside of cutscenes so I'm inclined to think it's something interacting with the game rather than something in the game itself.