Sliding rear window leaks in 3 spots. Leak poses the safety risk of mold growth inside the vehicle along with the potential of water getting inside of electrical components and air bag device compartments. The problem was reproduced and confirmed at the dealership, to which the plastic seal at the top of the rear window was confirmed to have failed in 3 locations. Dealership recommended replacing the entire back window and assembly with what they believe to be the same window assembly that failed. The only inspection completed on the vehicle to date has been the dealership GM certified technicians. Musty smell after rain and observed staining on the headliner is when the issue was first identified.