A system and a method for reducing annular pressure with a casing annulus pressure release system are described. The casing annulus pressure release system includes a controller, multiple sensors, and a pressure release sub-system disposed a wellbore annulus. The sensors sense wellbore conditions in the annular space and transmit signals representing the sensed wellbore conditions to the controller. The pressure release subsystem releases pressure in the annular space into the wellbore in response to a signal from the controller.