Cross-site scripting (XSS) vulnerability in admin/install.php in MantisBT before 1.2.19 and 1.3.x before 1.3.0-beta.2 allows remote attackers to inject arbitrary web script or HTML via the (1) admin_username or (2) admin_password parameter.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.