If Joomla and Moodle are working with Joomdle extension, and I have another application which can be configured to authenticate against a CAS server. Would it possible to configure it against Joomla if it is working with Joomdle in order to have SSO?
I don't know if Joomla can act as a CAS server.
However, even if this is true, you would not get SSO. You would only be able to log in with same credentials.
To get SSO, you would need to integrate the other application.