NASA photo captures strange bright light coming out of Mars

It's usual for CCD sensors in space to have such artifacts, due to energetic particles. It's true for a camera on Mars too, as the atmosphere is way too thin to protect from solar particles. http://www.eso.org/~ohainaut/ccd/CCD_artifacts.html

Could have also been something as benign as a dust plume. Still, it's far more likely it's an artifact.