Mettle SendPortal 3.0.1 and earlier contains a stored cross-site scripting (XSS) vulnerability in the template management functionality. The application fails to properly sanitize user-supplied input in the content parameter of the /templates endpoint, allowing an attacker to persistently inject malicious JavaScript code that is executed in the browsers of users who access the affected template.
https://github.com/mettle/sendportal
https://gist.github.com/WinBlah12/8dbc1eae788945c6ea6ab1a2cdfd7cb1