User Submitted Posts < 20260217 - Incorrect Authorization to Unauthenticated Category Restriction Bypass via 'user-submitted-category' Parameter

Description

The User Submitted Posts – Enable Users to Submit Posts from the Front End plugin for WordPress is vulnerable to Incorrect Authorization in all versions up to, and including, 20260113. This is due to the `usp_get_submitted_category()` function accepting user-submitted category IDs from the POST body without validating them against the admin-configured allowed categories stored in `usp_options['categories']`. This makes it possible for unauthenticated attackers to assign submitted posts to arbitrary categories, including restricted ones, by crafting a direct POST request with manipulated `user-submitted-category[]` values, bypassing the frontend category restrictions.