Always On VPN Security Updates May 2025

Once again, it’s the second Tuesday of the month, and Microsoft has published its monthly security updates for May 2025. Once again, this month includes many updates for the Windows Server Routing and Remote Access Service (RRAS) and an update for Active Directory Certificate Services (AD CS).

RRAS Updates

The Microsoft security updates for May 2025 address the following CVEs for Windows Server RRAS.

All the reported vulnerabilities in RRAS this month are information disclosure vulnerabilities, with exploitation unlikely. Most appear to be memory-related (null pointer references, out-of-bounds reads, etc.). None are Remote Code Execution (RCE) vulnerabilities, and none are rated Critical.

AD CS Update

This month’s update release also includes a single CVE addressing a denial of service (DoS) vulnerability in AD CS.

Additional Information

Microsoft May 2025 Security Updates

Always On VPN Security Updates April 2025

Microsoft has published its monthly security updates. Many updates address Routing and Remote Access Service (RRAS) vulnerabilities commonly used in Always On VPN deployments. In addition, an update addresses a vulnerability in Active Directory Certificate Services (AD CS). Always On VPN user and device authentication often rely on AD CS-issued certificates.

RRAS Updates

The April 2025 Microsoft security updates include the following CVEs for Windows Server RRAS.

Only one of these CVEs (26668) is a Remote Code Execution vulnerability. The others are information disclosure vulnerabilities. None of these vulnerabilities are rated Critical; all are rated Important.

AD CS Update

This month’s security update includes the following CVE for AD CS.

Additional Information

Microsoft April 2025 Security Updates

Always On VPN Security Updates February 2025

After a few months without any security updates directly affecting Microsoft Always On VPN administrators, the February 2025 security updates include fixes for two vulnerabilities in Windows Server Routing and Remote Access Service (RRAS) servers, commonly deployed to support Always On VPN.

RRAS Updates

This month’s updates for Windows Server RRAS cover the following publicly announced CVEs.

Importance

Both updates are for heap-based buffer overflow Remote Code Execution (RCE) vulnerabilities. These vulnerabilities are rated as important and require user interaction to execute, making exploitation less likely.

KB5014754

Importantly, this month’s release enables full enforcement of strong certificate mapping on Windows domain controllers by default. Full enforcement for strong certificate mapping was first introduced with Microsoft security update KB5014754. I’ve written about this recently, so hopefully, everyone is prepared! If your Always On VPN connections begin to fail after applying the February 2025 security updates to your domain controllers, your certificates may not be strongly mapped. Fortunately, there’s a workaround. You can learn more here.

Additional Information

Microsoft February 2025 Security Updates

Strong Certificate Mapping Enforcement February 2025

KB5014754 Certificate-based Authentication Changes on Windows Domain Controllers