Progress Sitefinity 10.1.6536 does not invalidate session cookies upon logouts. It instead tries to overwrite the cookie in the browser, but it remains valid on the server side. This means the cookie can be reused to maintain access to the account, even if the account credentials and permissions are changed.
Progress Sitefinity 9.1 has XSS via the Content Management Template Configuration (aka Templateconfiguration), as demonstrated by the src attribute of an IMG element. This is fixed in 10.1.
Progress Sitefinity 9.1 has XSS via file upload, because JavaScript code in an HTML file has the same origin as the application's own code. This is fixed in 10.1.