Cross-site scripting (XSS) vulnerability in bug_actiongroup_ext_page.php in MantisBT before 1.2.8 allows remote attackers to inject arbitrary web script or HTML via the action parameter, related to bug_actiongroup_page.php, a different vulnerability than CVE-2011-3357.
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.