Unable to RDP to Virtual Machine: CredSSP Encryption Oracle Remediation....?

Are you facing such types of error, Don't worry it will resolve your issue.

1. Change the policy settings on the client to temporarily gain RDP access to the servers. You can change the settings in Local Group Policy Editor. Execute gpedit.msc and browse to Computer Configuration / Administrative Templates / System / Credentials Delegation in the left pane as in the below screenshot.

2. Then double click on Encryption Oracle Remediation and change the Protection level from mitigated to vulnerable and apply as shown in below screenshot.

3. Congrats your issue is fixed now. Once forcefully update your group policy and take a remote it will work.

So what's the Root Cause behind it...?

To resolve a vulnerability issue with Credential Security Support Provider protocol (CredSSP), a monthly Windows update in May was applied which does two things:

1. Correct how Credential Security Support Provider protocol (CredSSP) validates requests during the authentication process

2. Change the group policy Encryption Oracle Remediation default setting from Vulnerable to Mitigated.

This RDP authentication issue can occur if the local client and the remote host have differing Encryption Oracle Remediation settings that define how to build an RDP session with CredSSP. If the server or client have different expectations on the establishment of a secure RDP session the connection could be blocked. There is the possibility that the current default setting could change from the tentative update and therefore impact the expected secure session requirement.