"Light" trail would be the extent too.
I rode with a guy today who was riding a cyclocross bike and it was far from capable of handling bumps and mud etc. The brakes weren't disc so they failed miserably on descents once a little mud and water touched them. The bike didn't have aux brakes so he had to ride on the hoods which wasn't ideal for handling the bumps, and his back wheel skipped often as he took corners with bumps. I realized today a cyclocross bike with drops would be my last choice on trails other than groomed trails.