New RDP security warning post Microsoft security update for April 2026 (4383105)

Overview

Starting with the April 2026 security update, the Remote Desktop Connection client shows new security warnings when you open RDP files. 

For more information on this Microsoft update, please refer to this article: 
Understanding security warnings when opening Remote Desktop (RDP) files

Problem Statement

As an administrator, I want users to launch the RDP sessions without additional security warnings.

Workaround # 1
Copy the approved access request credentials from SPP into the RDP client manually, for example:

Click on Fetch RDP Details and show icon 

Copy and paste the Computer ID from the access request into the RDP Client Computer field

Copy and paste the Username Connection String from the access request into the RDP client Username field

Click Connect

Workaround # 2
Use SCALUS to launch the RDP sessions. The tool can be downloaded from here

SCALUS is a tool provided by One Identity that can be installed on the client machine to allow users to use the Start RDP Session button to launch sessions from an access request and this way, the RDP file generated is signed when using this method. However, using SCALUS alone does not suppress the new RDP warning, an additional step in required to add the SCALUS certificate thumbprint to the client policy locally or by GPO in this location: 

- Navigate to Computer Configuration (Or User Configuration) 
-> Administrative Templates 
-> Windows Components 
-> Remote Desktop Services 
-> Remote Desktop Connection Client
- Enable the policy "Specify SHA1 thumbprints of certificates representing trusted .rdp publishers"
- Add the thumbprint of the SCALUS certificate.

Workaround # 3

Warning: This is not a long-term workaround and a future Windows update might remove support for this setting. Plan to transition your environment to work with the new security dialog.