The Gwolle Guestbook WordPress plugin before 4.2.0 does not sanitise and escape the gwolle_gb_user_email parameter before outputting it back in an attribute, leading to a Reflected Cross-Site Scripting issue in an admin page
XSS exists in admin/gb-dashboard-widget.php in the Gwolle Guestbook (gwolle-gb) plugin before 2.5.4 for WordPress via the PATH_INFO to wp-admin/index.php
PHP remote file inclusion vulnerability in the Gwolle Guestbook plugin before 1.5.4 for WordPress, when allow_url_include is enabled, allows remote authenticated users to execute arbitrary PHP code via a URL in the abspath parameter to frontend/captcha/ajaxresponse.php. NOTE: this can also be leveraged to include and execute arbitrary local files via directory traversal sequences regardless of whether allow_url_include is enabled.