Microsoft Releases Critical Security Update for CVE-2026-27199

Microsoft has released a critical security update addressing CVE-2026-27199, a vulnerability that could allow remote code execution on affected systems. The flaw impacts Windows 10, Windows 11, and Windows Server versions released between 2022 and 2024.

The vulnerability exists in the Windows Remote Procedure Call (RPC) service, where improper input validation could enable an attacker to execute arbitrary code with system privileges. Microsoft rates this as a 9.8 out of 10 on the CVSS scale, indicating critical severity.

Affected products include:

• Windows 10 version 21H2 through 22H2
• Windows 11 version 21H2 through 24H2
• Windows Server 2022 and 2025
• Windows Server Datacenter: Azure Edition

Microsoft has released patches through Windows Update and the Microsoft Update Catalog. Enterprise customers can also obtain the fixes via WSUS and SCCM. The company reports no evidence of active exploitation in the wild but urges immediate deployment of the updates.

To apply the security update:

1. Enable automatic updates or manually check for updates in Settings > Update & Security
2. Install all pending updates, particularly those labeled "Security Update"
3. Restart systems when prompted to complete installation
4. Verify installation through Windows Update history

Organizations with critical infrastructure should prioritize patching Windows Server systems first, as these pose the highest risk. Microsoft recommends testing updates in non-production environments before broad deployment, though the critical nature of this vulnerability may warrant expedited patching.

Additional guidance is available through Microsoft's Security Update Guide at docs.microsoft.com/security-updates. Users can also subscribe to Microsoft Security Response Center alerts for future vulnerability notifications.

This marks Microsoft's third critical security update in 2026, following similar RPC-related vulnerabilities addressed in January and March. The company continues to enhance its vulnerability detection and response capabilities to protect users from emerging threats.