The WP Event Solution (Eventin) plugin for WordPress is vulnerable to Missing Authorization in versions up to, and including, 4.1.22 via the create_item() handler for the /wp-json/eventin/v2/orders REST endpoint. The endpoint's create_item_permissions_check() function only verifies a wp_rest nonce (which is leaked to every visitor through the etn-public script's localized_data_obj on every frontend page) and accepts a user-supplied 'status' value in prepare_item_for_database() with no whitelist validation. This makes it possible for unauthenticated attackers to create etn-order posts with status='completed' that are counted as sold by etn_get_sold_tickets_by_event(); because the auto-cleanup wp_schedule_single_event() in create_item() only fires for status='pending' orders, the forged completed orders persist indefinitely and exhaust ticket inventory.
Attack Parameters
Impact Assessment
CVSS Vector v3.1