All posts in category Patch Tuesday

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

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by Richard M. Hicks on April 14, 2026  •  Permalink
Posted in Always On VPN, AOVPN, CVE, device tunnel, Enterprise, enterprise mobility, IKEv2, Infrastructure, Microsoft, Patch Tuesday, RCE, Remote Access, routing and remote access service, RRAS, Security, Security Update, Update, user tunnel, VPN, Vulnerability, Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, Windows Server 2022, Windows Server 2025
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Posted by Richard M. Hicks on April 14, 2026

https://directaccess.richardhicks.com/2026/04/14/always-on-vpn-ikev2-security-vulnerability-april-2026/

Always On VPN Security Updates July 2025

Patch Tuesday has arrived, and, unlike last month, it’s a busy month for Always On VPN administrators. The June 2025 Microsoft security updates address a whopping 16 (!) vulnerabilities in the Windows Routing and Remote Access Service (RRAS). Notably, DirectAccess administrators are once again impacted by a critical vulnerability in the Windows KDC Proxy Service (KPSSVC) this month.

RRAS

As stated previously, this month’s update addresses 16 unique CVEs in Windows Server RRAS. All are memory-related buffer overflows and out-of-bounds reads, indicating that a security researcher was recently probing for vulnerabilities in RRAS.

While all the above CVEs are Remote Code Execution (RCE) and Information Disclosure vulnerabilities, none are rated as Critical; all are rated as Important. This means exploitation is unlikely, but administrators are encouraged to update as soon as possible.

KDC Proxy

This month’s security update includes another Critical RCE in the Windows KDC Proxy Service (KPSSVC).

The KDC Proxy is enabled by default when DirectAccess is configured. By design, this means the service is exposed to the public Internet, posing a significant risk to organizations using DirectAccess for secure remote access. Administrators are urged to update their systems immediately to avoid compromise.

Additional Information

Microsoft July 2025 Security Updates

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by Richard M. Hicks on July 8, 2025  •  Permalink
Posted in Always On VPN, AOVPN, authentication, CVE, DirectAccess, KDC Proxy, Microsoft, Patch Tuesday, routing and remote access service, RRAS, Security, Security Update, Update, VPN, Vulnerability, Windows 10, Windows Server 2016, Windows Server 2019, Windows Server 2022, Windows Server 2025
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Posted by Richard M. Hicks on July 8, 2025

https://directaccess.richardhicks.com/2025/07/08/always-on-vpn-security-updates-july-2025/