Monstra CMS 3.0.4 contains a cross-site scripting vulnerability via the registration form (i.e., the login parameter to users/registration). An attacker can inject arbitrary script in the browser of an unsuspecting user in the context of the affected site. This can allow the attacker to steal cookie-based authentication credentials and launch other attacks.
View the template here CVE-2018-11473.yaml
References:
https://github.com/monstra-cms/monstra/issues/446