The WP Event Solution (Eventin) plugin for WordPress is vulnerable to Missing Authorization in versions up to, and including, 4.1.22 via the createitem() handler for the /wp-json/eventin/v2/orders REST endpoint. The endpoint's createitempermissionscheck() function only verifies a wprest nonce (which is leaked to every visitor through the etn-public script's localizeddataobj on every frontend page) and accepts a user-supplied 'status' value in prepareitemfordatabase() 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 etngetsoldticketsbyevent(); because the auto-cleanup wpschedulesingleevent() in createitem() only fires for status='pending' orders, the forged completed orders persist indefinitely and exhaust ticket inventory.

Unauthenticated Broken Access Control in WP Event SOlution <= 4.1.8 versions.