index.php in gBook 1.4 allows remote attackers to bypass authentication and gain administrative privileges by setting the login parameter to true.

Cross-site scripting (XSS) vulnerability in GBook for Php-Nuke 1.0 allows remote attackers to inject arbitrary web script or HTML via multiple parameters, including (1) name, (2) email, (3) city, and (4) message, which do not use the <script> and <style> tags, which are filtered by PHP-Nuke.

Cross-site scripting (XSS) vulnerability in GBook for PHP-Nuke 1.0 allows remote attackers to inject arbitrary web script or HTML via cookies that are stored in the $_COOKIE PHP variable, which is not cleansed by PHP-Nuke.

Cross-site scripting (XSS) vulnerability in gbook.cgi in gBook before 1.0.2 allows remote attackers to inject arbitrary web script or HTML via the User-Agent HTTP header field.