User Submitted Posts < 20230901 - Contributor+ Stored XSS via Shortcode

Description

The User Submitted Posts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's [usp_gallery] shortcode in versions up to, and including, 20230811 due to insufficient input sanitization and output escaping on user supplied attributes like 'before'. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.