snipe-it before 8.7.0 Checkout Request Counter Integrity Failure

snipe-it before 8.7.0 contains an incorrect calculation vulnerability in checkout request handling that allows authenticated users to corrupt the assets.requests_counter through duplicate submissions and cancellations without active requests. Attackers can repeatedly call cancel endpoints without active requests to drive the counter negative, or submit duplicate checkout requests to inflate the counter, misrepresenting pending demand in the admin queue.