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

November 2024 Microsoft Security Updates and DirectAccess

With the November 2024 security updates, Microsoft disclosed a vulnerability (CVE-2024-43639) in the Windows Server KDC Proxy service. This is a Remote Code Execution (RCE) vulnerability with a max severity rating of Critical. If you still use Microsoft DirectAccess for remote access, you’ll want to pay close attention to this bulletin.

KDC Proxy and DirectAccess

When DirectAccess is installed and configured, the KDC Proxy Service is enabled automatically and by default. By design, DirectAccess servers are exposed to the Internet, which significantly increases the risk of this vulnerability. Organizations that have deployed DirectAccess are encouraged to update their systems immediately.

Workaround

There is no known workaround available at this time. Apply the latest security updates to mitigate this risk.

Additional Information

Windows KDC Proxy Remote Code Execution Vulnerability

Microsoft DirectAccess Formally Deprecated

Always On VPN Security Updates October 2024

Microsoft has released the October 2024 security updates, and numerous issues may impact Always On VPN administrators. Although many CVEs affect Always On VPN-related services that are Remote Code Execution (RCE) vulnerabilities, none are critical this cycle.

RRAS Updates

This month, Microsoft has provided 12 updates for the Windows Server Routing and Remote Access Service (RRAS), commonly deployed to support Always On VPN deployments. Most of these CVEs involve overflow vulnerabilities (heap and stack), input validation weaknesses, and buffer over-read and overflow vulnerabilities. All are rated important, and there are no known exploits currently.

CVE-2024-38212

CVE-2024-38261

CVE-2024-38265

CVE-2024-43453

CVE-2024-43549

CVE-2024-43564

CVE-2024-43589

CVE-2024-43592

CVE-2024-43593

CVE-2024-43607

CVE-2024-43608

CVE-2024-43611

Related Updates

In addition to the updates above, Microsoft also released fixes for security vulnerabilities in various related services that are important to Always On VPN administrators.

Windows Network Address Translation (NAT)

The following CVEs address denial of service vulnerabilities in the Network Address Translation (NAT) service.

CVE-2024-43562

CVE-2024-43565

Certificate Services

Always On VPN administrators will also find updates for CVEs affecting various certificate services-related components.

CVE-2024-43545OCSP Denial of Service Vulnerability

CVE-2024-43541Simple Certificate Enrollment Protocol (SCEP) Denial of Service Vulnerability

CVE-2024-43544Simple Certificate Enrollment Protocol (SCEP) Denial of Service Vulnerability

Recommendations

Always On VPN administrators are encouraged to update systems as soon as possible. However, since none of the CVEs is rated Critical, updates can be applied during standard update windows.

Additional Information

Microsoft October 2024 Security Updates