Stripe Payment Forms by WP Full Pay < 8.5.2 - Unauthenticated Payment Intent Amount Manipulation

The Stripe Payment Forms by WP Full Pay WordPress plugin before 8.5.2 does not verify that the caller owns the Stripe payment intent referenced by two unauthenticated payment-form AJAX actions, allowing an unauthenticated visitor — using a nonce that is embedded in every public page containing a payment form — to change the amount of a payment intent that the Stripe Payment Forms by WP Full Pay WordPress plugin before 8.5.2 then updates server-side through the Stripe API with the store's secret key. An ownership check added in 8.5.0 was applied to only one payment-intent handler, leaving the pricing-recalculation and payment-intent-update actions unprotected against amount manipulation.