The invention relates to a shock absorber with a housing, and an inner pipe arranged in the housing, a piston rod, a piston and which piston divides the interior of the inner pipe into a lower chamber and an upper chamber, a first valve arrangement which is arranged on the piston, a second valve arrangement which is arranged at the upper end of the inner pipe and a third valve arrangement which is arranged at the lower end of the inner pipe. The shock absorber is distinguished by the fact that at least one proportional flow-control valve is arranged between a first connecting element of the lower chamber of the inner pipe and a second connection element at the upper chamber of the inner pipe.