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.
https://www.mantisbt.org/bugs/view.php?id=17938
https://www.mantisbt.org/bugs/view.php?id=17937
https://github.com/mantisbt/mantisbt/commit/6d47c047
https://github.com/mantisbt/mantisbt/commit/132cd6d0