The All-In-One Security (AIOS) – Security and Firewall plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to and including 5.4.7. This is due to insufficient input sanitization in the get_rest_route() function and missing output escaping in the column_default() method of the debug log list table. When the 'Disable REST API for non-logged in users' feature (aiowps_disallow_unauthorized_rest_requests) is enabled alongside debug logging (aiowps_enable_debug), an unauthenticated attacker can embed arbitrary HTML or JavaScript in the REST request path. The path is retrieved via urldecode($_SERVER['REQUEST_URI']), which decodes URL-encoded payloads into literal HTML characters. This decoded, unsanitized value is concatenated directly into a debug log message and stored in the database. When an administrator navigates to the AIOS Dashboard Debug Logs page, the column_default() method returns the raw database value without escaping, and the parent list table echoes it directly, causing JavaScript execution in the administrator's browser session. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute when an administrator views the debug log page, enabling nonce theft, privileged AJAX/REST actions, and potential full site compromise.