Say I have an application written in some language and framework (Python + flask, for instance), and have a great deal of the functionality requiring login, and authentication via JWT.
Now I want to create a new module built as an app, possibly made in with different tools (django, for instance, or maybe even in a different language), in its own small separate project. This new mini app, which is more a module than a complete app, will receive some information from the user that was entered in the other app, but also was thinking about sending in the token, so that the user doesn't have to login again into this new "app". In essence, upon a certain condition being met, the user will be redirected to a new page (which is where the new app comes in) while sending the necessary authentication information and some other information. I have never done this before, but I believe/hope I could find a way to do it.
Would this be a sane/safe way of constructing this application, or am I exposing my system to great dangers? If the latter, what is the worst thing an attacker could do? Basically, is this in violation of any principles of security?