An energy absorber reduces an excessive load between an object and an assembly in an overload event. The energy absorber includes an absorber cylinder and a piston device with an absorber piston and a piston rod. A first chamber of an absorber chamber is filled with a field-sensitive absorber fluid. The piston has an absorber valve with an absorber duct extending in an axial direction and being subject to a selective field of a field generating device. A ratio of the outer diameter of the piston rod to an outer diameter of the absorber piston is greater than 0.6 and the first chamber extends in a space around the piston rod. During the relative motion of the fastener and the holding device the field-sensitive absorber fluid is urged through the damping duct of the absorber piston.