Session is cached for OpenID and OAuth2 if `redirect` is not used

Summary

Unauthenticated user can access credentials of last authenticated user via OpenID or OAuth2 where the authentication URL did not include redirect query string.

For example:

• Project is configured with OpenID or OAuth2
• Project is configured with cache enabled
• User tries to login via SSO link, but without redirect query string
• After successful login, credentials are cached
• If an unauthenticated user tries to login via SSO link, it will return the credentials of the other last user

The SSO link is something like https://directus.example.com/auth/login/openid/callback, where openid is the name of the OpenID provider configured in Directus

Details

This happens because on that endpoint for both OpenId and Oauth2 Directus is using the respond middleware, which by default will try to cache GET requests that met some conditions. Although, those conditions do not include this scenario, when an unauthenticated request returns user credentials. For OpenID, this can be seen here: https://github.com/directus/directus/blob/main/api/src/auth/drivers/openid.ts#L453-L459 And for OAuth2 can be seen here https://github.com/directus/directus/blob/main/api/src/auth/drivers/oauth2.ts#L422-L428

PoC

• Create a new Directus project
• Set CACHE_ENABLED to true
• Set CACHE_STORE to redis for reliable results (if using memory with multiple nodes, it may only happen sometimes, due to cache being different for different nodes)
• Configure REDIS with redis string or redis host, port, user, etc.
• Set AUTH_PROVIDERS to openid
• Set PUBLIC_URL to the the main URL of your project . For example, PUBLIC_URL: http://localhost:8055
• Configure AUTH_OPENID_CLIENT_ID, AUTH_OPENID_CLIENT_SECRET, AUTH_OPENID_ISSUER_URL with proper OpenID configurations
• Be sure that on OpenID external app you have configured Redirect URI to http://localhost:8055/auth/login/openid/callback
• Run Directus
• Open the SSO link like http://localhost:8055/auth/login/openid/callback
• Do the authentication on the OpenID external webpage
• Verify that it you got redirected to a page with a JSON including access_token property
• Be sure all anonymous mode windows are closed
• Open an anonymous window and go to the SSO Link http://localhost:8055/auth/login/openid/callback and see you have the same credentials, even though you don't have any session because you are in anonymous mode

Impact

All projects using OpenID or OAuth 2, that does not include redirect query string on loggin in users.