Mantis is prone to an HTML-injection vulnerability because it fails to properly sanitize user-supplied input before using it in dynamically generated content. Successful exploits will allow attacker-supplied HTML and script code to run in the context of the affected browser, potentially allowing the attacker to steal cookie-based authentication credentials or to control how the site is rendered to the user. Other attacks are also possible. Mantis 1.2.2 is vulnerable other versions may also be affected.
Updates are available please see the references for more information.