Cross-site scripting (XSS) vulnerability in helper_api.php in MantisBT 1.1.0a1 through 1.2.x before 1.2.18, when Extended project browser is enabled, allows remote attackers to inject arbitrary web script or HTML via the project cookie.
https://www.mantisbt.org/bugs/view.php?id=17890
https://github.com/mantisbt/mantisbt/commit/511564cc
http://www.debian.org/security/2015/dsa-3120
http://secunia.com/advisories/62101