On [XXX] 2024 my wife, son, and I were sitting at a stop light on [XXX] at approximately 16:40 hours when we heard a loud pop in the vehicle and my wife's head was pushed forward by the passenger side seat head rest, causing pain to my wife's head and neck, and shoulder muscles. Upon inspection of the head rest, it had become separated in the middle (pictures attached). Vehicle is equipped with the active head restraint system. My wife has not received medical attention yet but is quite sore this morning. We will contact our dealer to replace the head rest (and the driver's side head rest) and request the defective head rest be returned to us so it is available for NHTSA inspection. The vehicle has not yet been inspected by the manufacturer, police, insurance rep, or others yet. There were no warning lamps, messages, or other symptoms of the problem prior to the failure. This happened suddenly without any warning while we were stopped at a traffic light. Our safety was put at risk by the sudden failure and violent expansion to the head rest causing pain to my wife. Had this occurred on the driver's side while the vehicle was in motion, it could have caused a motor vehicle crash resulting in severe injury, property damage, or even death. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)