HTML Injection is a vulnerability which occurs in web applications that allows users to insert HTML code via a specific parameter. This type of attack can be used in combination with some sort of social engineering in order to trick valid users of the application to open malicious websites or to insert their credentials in a fake login form that it will redirect the users to a page that captures cookies and credentials. In this tutorial we are going to see how we can exploit this vulnerability effectively once it is discovered. For the purposes of the article the Mutillidae will be used as the vulnerable application.”]
Source: https://informationsecuritybuzz.com/news/html-injection/