The popup-builder plugin before 3.64.1 for WordPress allows information disclosure and settings modification, leading to in-scope privilege escalation via admin-post actions to com/classes/Actions.php. By sending a POST request to wp-admin/admin-post.php, an authenticated attacker with minimal (subscriber-level) permissions can modify the plugin's settings to allow arbitrary roles (including subscribers) access to plugin functionality by setting the action parameter to sgpbSaveSettings, export a list of current newsletter subscribers by setting the action parameter to csv_file, or obtain system configuration information including webserver configuration and a list of installed plugins by setting the action parameter to sgpb_system_info.