A valve for a cold gas generator for an airbag in a vehicle includes: a valve chamber; a control chamber; a control piston; an overflow channel; a retaining element; and a shutoff element. The valve chamber includes an inlet from the cold gas generator and an outlet to the airbag. The control piston separates the control chamber and the valve chamber. The control piston is movable between an open position and a closed position, the control piston releasing the outlet in the open position and closing it in the closed position. The control piston has (i) a first active piston surface on the side of the valve chamber, and (ii) a second active piston surface on the side of the control chamber. The first piston surface is smaller than the second piston surface. The overflow channel fluidically connects the valve chamber and the control chamber to one another.