Vulnerability in Redash OAuth2 flows due to misuse of state field (should be a nonce)

Summary

Redash is a package for data visualization and sharing. In Redash version 10.0 and prior, the implementation of Google Login (via OAuth) incorrectly uses the `state` parameter to pass the next URL to redirect the user to after login. The `state` parameter should be used for a Cross-Site Request Forgery (CSRF) token, not a static and easily predicted value. This vulnerability does not affect users who do not use Google Login for their instance of Redash. A patch in the `master` and `release/10.x.x` branches addresses this by replacing `Flask-Oauthlib` with `Authlib` which automatically provides and validates a CSRF token for the state variable. The new implementation stores the next URL on the user session object. As a workaround, one may disable Google Login to mitigate the vulnerability.