Always On VPN IKEv2 Security Vulnerability April 2026

Microsoft published its Security Updates for April 2026 today, and the good news is that there are no Windows Server Routing and Remote Access (RRAS) vulnerabilities this month. However, they disclosed a critical remote code execution (RCE) vulnerability that impacts deployments using Internet Key Exchange version 2 (IKEv2).

IKE Service Extensions RCE

CVE-2026-33824 addresses a security vulnerability in the Windows Internet Key Exchange (IKE) Service Extensions. This vulnerability is a Remote Code Execution (RCE) vulnerability, with a CVSS 3.1 base score of 9.8 (Critical). Always On VPN implementations that use the device tunnel or IKEv2 for the user tunnel are affected.

Impact

This vulnerability presents a unique challenge to Always On VPN administrators as IKEv2 is required to support device tunnel connections. Some implementations also use IKEv2 for the user tunnel. In either case, the vulnerable VPN server, often domain-joined, is reachable from the Internet, greatly increasing the attack surface and exposure to this vulnerability.

Recommendations

For deployments that use IKEv2 (device or user tunnel), administrators should update their RRAS server as soon as possible to protect against potential attacks on this service.

Not Using IKEv2?

If you are not using the device tunnel or IKEv2 for the user tunnel, ensure the following IKEv2 ports are blocked at the edge firewall.

  • Inbound UDP port 500 (IKE)
  • Inbound UDP port 4500 (IKE NAT-T)

In addition, consider disabling IKEv2 on the RRAS server by opening an elevated command window and running the following command.

netsh.exe ras set wanports device = "WAN Miniport (IKEv2)" rasinonly = disabled ddinout = disabled ddoutonly = disabled maxports = 0

Optionally, you can use the Routing and Remote Access management console (rrasmgnt.msc) to perform this task.

  1. Right-click on Ports and choose Properties.
  2. Select WAN Miniport (IKEv2).
  3. Click Configure.
  4. Uncheck Remote access connections (inbound only).
  5. Uncheck Demand-dial routing connection (inbound and outbound).
  6. Enter 0 in the Maximum ports field.
  7. Click Ok.

Additional Information

Microsoft Security Updates for April 2026

CVE-2026-33824 – Windows Internet Key Exchange (IKE) Service Extension RCE

RemoteAccess Service Hangs in Windows Server 2025

For Always On VPN administrators using the Routing and Remote Access Service (RRAS) on Windows Server 2025, you’ve likely encountered issues with service restarts and system reboots since migrating to the latest release of the Windows server operating system. I’ve experienced this myself, and many of my customers and Discord users have raised the same complaints.

Service Hang

Attempting to restart the RemoteAccess service after the server has accepted at least one VPN connection causes the service to hang. In addition, many have reported that the server hangs and eventually blue-screens during a shutdown or restart.

Resolution

Unfortunately, there is no workaround or fix for this issue today. However, hope is on the horizon.

Coming Soon

I have several customers with open support cases for this issue. Microsoft has informed them that a fix is due out soon, perhaps with the April security updates (April 14, 2026). I performed validation testing with the latest Insider build for Windows Server 2025 and can confirm that Microsoft fixed the issue in this release. Unfortunately, I wouldn’t recommend running an Insider build in production, so hang on (pun intended!) for the April security updates.

Additional Information

Always On VPN on Discord

Windows Server Insider Builds

Always On VPN Windows Server 2025 Binding Handle is Invalid Error

Microsoft released Windows Server 2025 late last year. I’ve been doing extensive testing with the Routing and Remote Access (RRAS) role, commonly deployed to support Always On VPN client connections. I heavily use automation to deploy VPN servers in my lab and for large customer deployments, and after deploying some new Windows Server 2025 machines, I encountered the “binding handle is invalid” error message when running specific commands.

VPN Ports

By default, Windows Server RRAS enables IKEv2 for Remote Access (RAS) and SSTP for RAS and Routing. Each is provisioned with 128 ports. Often, these settings are updated because there are not enough ports to support expected concurrent connections. Also, SSTP should not be enabled for Routing as it is not required, and PPPoE is enabled for Routing, which is also not required. The best practice is to disable any protocols and services that are not being used.

Although updating these settings can be updated in the GUI (rrasmgmt.msc), automating these changes requires command line configuration.

Netsh

Here’s the command to configure additional SSTP ports and disable Routing using netsh.exe.

netsh.exe ras set wanports device = “WAN Miniport (SSTP)” rasinonly = enabled ddinout = disabled ddoutonly = disabled maxports = 500

However, running this command returns the following error message.

“The binding handle is invalid.”

PowerShell

You might be wondering why we don’t use PowerShell for these tasks. Sadly, not all these settings are exposed via PowerShell. For example, with the native Set-VpnServerConfiguration PowerShell command, you can set the number of ports for IKEv2, SSTP, L2TP, and GRE. However, you cannot turn these protocols on or off entirely as you can with netsh.exe commands.

Here’s an example of setting up VPN server port configuration using PowerShell.

Set-VpnServerConfiguration -SstpPorts 500 -Ikev2Ports 500 -PassThru

Note: You must restart the server (not just the RemoteAccess service) when increasing the number of ports beyond the default setting of 128.

Set-VpnServerConfiguration does not support configuration for PPTP. However, PPTP is disabled by default on Windows Server 2025.

Backup and Restore

This issue will also impede the ability to back and restore the RRAS configuration using netsh.exe. You can back up the RRAS configuration by running the following command.

netsh.exe ras dump | Out-File rasconfig.txt -Encoding ascii

You can restore the configuration by running the following command.

netsh.exe exec .\rasconfig.txt

However, you will receive “binding handle is invalid” error when running this command.

AovpnTools

Be advised that the following functions in my AovpnTools PowerShell module use netsh.exe commands that will return the “binding handle is invalid” error message when configuring Windows Server 2025 servers.

Workaround

Until Microsoft resolves this issue, administrators must use a combination of the native PowerShell commands and manual configuration using the Routing and Remote Access management console (rrasmgmt.msc) to implement these settings changes. When backing up and restoring the RRAS configuration, additional configuration will be required after configuration import to ensure the VPN server port configuration is configured correctly.

Additional Information

Always On VPN PowerShell Module on GitHub