Query String is not allowed in redirect_uri for Azure AD

Problem:

Customer configures the following redirect URLs for his registered application in Azure AD

and issues the following request to authenticate to Azure AD:

GET https://login.microsoftonline.com/<tenant id>/oauth2/authorize?client_id=<app id>&redirect_uri=https%3a%2f%2flocalhost%3a44396%2fbac%2faad%3freqId%3dA123&response_mode=form_post&….

After logging in he is redirected to https://localhost:44396/bac/aad instead of https://localhost:44396/bac/aad ?reqId=A123.

The redirected URL does not have anything after the query string.

Root Cause:

The behavior is by design.  This is an Azure AD’s security feature to prevent Covert Redirect attack.

Resolution:

We recommend customer to make use of the ‘state’ parameter instead of using query string to preserve the state of the request.