Welcome to Android Central! Did this just start? Any recent trauma, drops, or water exposure? Is it only the rear-facing camera, or the front-facing camera as well? Does it persist after a reboot?
Try wiping the cache partition. Follow the steps in this video, but instead of selecting Wipe Data/Factory Reset, make sure you select Wipe Cache Partition. When complete, then select Reboot System Now.
https://www.youtube.com/watch?v=KPEubOQVuQQ