All posts in category routing and remote access service

Always On VPN Security Updates July 2026

Microsoft released the July 2026 Windows security updates today, including several fixes that directly affect Always On VPN deployments. This month’s release addresses vulnerabilities in the Secure Socket Tunneling Protocol (SSTP), Internet Key Exchange (IKE), and the Routing and Remote Access Service (RRAS), making it an important update for organizations using Always On VPN.

SSTP Remote Code Execution

The highest-priority issue for Always On VPN administrators is a Remote Code Execution (RCE) vulnerability affecting the Secure Socket Tunneling Protocol (SSTP). SSTP is commonly used for Always On VPN user tunnel connections. Because SSTP is, by design, exposed directly to the Internet, vulnerabilities affecting this protocol deserve immediate attention. Microsoft rates this vulnerability as Critical with a CVSS base score of 8.1.

CVE-2026-50694 – Windows SSTP Remote Code Execution Vulnerability

IKE Vulnerabilities

These vulnerabilities primarily affect IKE-based VPN connections and could allow an attacker to disrupt VPN connectivity using specially crafted packets. While Microsoft rates these vulnerabilities as Important rather than Critical, organizations should still plan to deploy these updates promptly.

CVE-2026-50721 – IKEv1 Denial of Service via RSA-SHA1 authentication payload

CVE-2026-50722 – IKEv2 Denial of Service via RSA-SHA1 authentication payload

CVE-2026-12413 – IKEv2 Denial of Service via malformed fragmentation

CVE-2026-50696 – IKE Protocol Denial of Service Vulnerability

RRAS Vulnerabilities

The July 2026 security updates also address several vulnerabilities in the Windows Server Routing and Remote Access Service (RRAS). All are rated Important by Microsoft.

CVE-2026-57096 – Windows RRAS Elevation of Privilege Vulnerability

CVE-2026-49791 – Windows RRAS Elevation of Privilege Vulnerability

CVE-2026-50451 – Windows RRAS Elevation of Privilege Vulnerability

Summary

The SSTP RCE vulnerability is particularly concerning because the service is typically exposed to the Internet and could allow an unauthenticated attacker to execute code remotely. Organizations should prioritize deployment of this update. The IKE and RRAS vulnerabilities are rated Important and can generally be addressed during the next scheduled maintenance window, although administrators should avoid unnecessary delays in applying these updates.

Microsoft AD CS Adds Post-Quantum Cryptography Support with ML-DSA

Despite predictions of its decline, Microsoft Active Directory Certificate Services (AD CS) continues to evolve. Following significant enhancements introduced in late 2025, including CRL partitioning and support for 16K database pages, the May 2026 update adds another important capability: support for Post-Quantum Cryptography (PQC).

ML-DSA

Specifically, the May 2026 update adds support for ML-DSA-44, ML-DSA-65, and ML-DSA-87 in Windows Server 2025 for AD CS. This enables administrators to begin evaluating post-quantum cryptographic algorithms and assessing PQC readiness in enterprise PKI environments

Configuration

After applying the May 2026 update to an issuing Certification Authority (CA), administrators will find new PQC algorithms under the Algorithm name drop-down list, as shown here.

Note: If you don’t see these new algorithms, ensure you have selected Key Storage Provider from the Provider Category drop-down list. In addition, ensure that you select Signature on the Request Handling tab.

Test Results

Initial testing across common enterprise certificate scenarios produced mixed results. While PQC works well in some scenarios, other workloads still show limitations.

Code Signing

Code signing with an ML-DSA-44 certificate issued by AD CS works perfectly. For example, I can use Set-AuthenticodeSignature to sign a PowerShell script, as shown here.

Viewing the file’s properties shows that the encryption algorithm used to sign the file was ML-DSA-44, as expected.

IIS

TLS-based workloads proved more challenging. Attempts to configure an HTTPS binding in IIS failed with the following error message.

There was an error while performing this operation. A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520).

RRAS and SSTP

Similar limitations occurred when testing remote-access VPN scenarios using RRAS and SSTP. Specifically, configuring a PQC TLS certificate for SSTP in RRAS failed. Although I was able to assign the certificate using Set-RemoteAccess, the RemoteAccess service failed to start.

Remote Desktop

Unfortunately, using PQC certificates for RDP also fails. Although I could assign the PQC certificate to the RDP listener, clients fail to connect using RDP and return the following error message.

This computer can’t connect to the remote computer. Try connecting again. If the problem continues, contact the owner of the remote computer or your network administrator.

Error code: 0x904
Extended error code: 0x7

Summary

The May 2026 update marks an important milestone for AD CS by introducing initial support for PQC algorithms, allowing organizations to begin evaluating ML-DSA certificates in enterprise environments. Early testing shows promising results for signing scenarios such as code signing; however, broader infrastructure workloads, including TLS, VPN, and Remote Desktop, remain limited today. Although PQC support is still in its early stages, these updates demonstrate Microsoft’s ongoing investment in AD CS and provide administrators with an opportunity to begin preparing their PKI environments for the post-quantum future. Additional PQC enhancements, including ML-KEM support and broader ecosystem integration, are anticipated in future Windows updates.

Additional Information

Microsoft May 2026 Security Updates (KB5087539)

Post Quantum Cryptography in the Enterprise

IIS TLS Certificate Deployment with CertKit

With public TLS certificate lifetimes shrinking to just 47 days by 2029, administrators must find ways to automate certificate enrollment and renewal for workloads that require them. One of the most common is Microsoft Internet Information Services (IIS). I’ve been using CertKit.io to handle this process for workloads like Always On VPN and DirectAccess, so it made sense to migrate my public-facing IIS servers to this solution as well. The migration went smoothly, but I encountered an unexpected issue when deploying a new IIS server using CertKit.

CertKit Agent

CertKit Agents make loading certificates on the server a breeze. The CertKit agent automatically detects installed software (e.g., Terminal Services, RRAS, DirectAccess, IIS, etc.) and handles the server-side process of assigning the TLS certificate to the application. For RRAS and DirectAccess, it works perfectly. For an IIS server with an HTTPS binding and TLS certificate already configured, it works without issue as well. However, I ran into a snag when I tried to deploy a certificate to a brand-new IIS server.

New Server

After installing the CertKit agent on an IIS server, it searches for existing HTTPS web bindings to identify the workload. However, on a freshly installed IIS server, no HTTPS bindings have been configured yet, so the agent doesn’t recognize the IIS workload.

Of course, you could create an HTTPS web binding before installing the agent, but you’ll need a TLS certificate first. This introduces the classic “chicken and egg” scenario. 🤪 Fortunately, there are a few ways to resolve the issue.

Windows Certificate Store

With this method, you configure the CertKit agent to download and install the certificate into the local computer certificate store on the IIS server. Once complete, you can create the HTTPS binding in the IIS Manager console or by using PowerShell. After that, restart the CertKit agent service by running the following PowerShell command.

Restart-Service -Name certkit-agent -PassThru

The IIS workload will now appear in the agent’s Software list. At that point, you can delete the Windows certificate store configuration and replace it with the IIS configuration.

Self-Signed Certificate

Using this method before installing the CertKit agent allows the agent to automatically discover IIS after installation, which can be helpful when deploying IIS servers programmatically. First, create a short-lived certificate (one day in this example) and configure the IIS site binding by running the following PowerShell commands.

			
$Hostname = 'www.example.net'
$Certificate = New-SelfSignedCertificate -DnsName $Hostname -CertStoreLocation 'Cert:\LocalMachine\My' -KeyAlgorithm RSA -KeyLength 2048 -HashAlgorithm SHA256 -NotAfter (Get-Date).AddDays(1) -TextExtension @('2.5.29.37={text}1.3.6.1.5.5.7.3.1')
$Params = @{
    Name                  = 'Default Web Site'
    BindingInformation    = '*:443:'
    Protocol              = 'https'
    CertificateThumbPrint = $Certificate.Thumbprint
    CertStoreLocation     = 'Cert:\LocalMachine\My'
    
}
New-IISSiteBinding @Params

		

Once complete, run iisreset.exe to apply the changes. Now, when you install the CertKit agent, it will automatically detect IIS, and you can assign your public TLS certificate accordingly. You can delete the old self-signed certificate later if desired.

Summary

If you’re automating server builds, the self-signed certificate approach is typically the easiest because it enables IIS discovery immediately. For ad-hoc deployments, installing to the Windows certificate store first is usually the quickest option.

Additional Information

CertKit.io

CerKit Agent Support for Always On VPN SSTP and DirectAccess IP-HTTPS TLS Certificates

Richard M. Hicks Consulting, Inc.

Microsoft MVP

TechMentor 2026

Consulting

Pluralsight

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All posts in category routing and remote access service

Always On VPN Security Updates July 2026

SSTP Remote Code Execution

IKE Vulnerabilities

RRAS Vulnerabilities

Summary

Like this:

Microsoft AD CS Adds Post-Quantum Cryptography Support with ML-DSA

ML-DSA

Configuration