After removing the third row seating mechanism, it was noticed that significant rust has occured at the forward mounting point for the hinge device around the welds and heat affected zone of the mounting bracket. No rust was visible from the wheel well due to the textured undercoating until the undercoating was removed. Rust had penetrated through the body and seat mount, resulting in a potentially unsafe condition for third row passengers. Recommend owners have this area checked on a regular basis to prevent safety concerns and remediate corrosion as necessary.