Docassemble is an expert system for guided interviews and document assembly. Prior to 1.4.97, a user could type HTML into a field, including the field for the user's name, and then that HTML could be displayed on the screen as HTML. The vulnerability has been patched in version 1.4.97 of the master branch.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.