Critical Microsoft Vulnerability Exposes Windows Systems to Remote Attacks

Microsoft confirms active exploitation attempts targeting CVE-2026-21524. This critical-severity vulnerability allows attackers to remotely execute malicious code. Unauthorized system access is possible without user interaction.

Affected products include Windows 10 versions 21H2 through 23H2 and Windows Server 2022. Systems lacking July 2024 security updates are vulnerable. The flaw resides in the Windows Remote Procedure Call (RPC) component. Attackers exploit improper memory handling during network requests.

CVSS v3.1 scoring rates this vulnerability 9.8 (Critical). Successful attacks compromise entire systems. Data theft and ransomware deployment are likely outcomes. Microsoft detected targeted attacks before public disclosure.

Apply security updates immediately. Use the Microsoft Security Update Guide for patch verification. Block TCP port 135 at firewalls as temporary mitigation. Enable Windows Defender Attack Surface Reduction rules.

The vulnerability was reported through Microsoft's coordinated disclosure program. Patches released on July 9, 2024. Microsoft credits external researchers for discovery. Monitor systems for anomalous RPC traffic patterns.

Enterprises should prioritize patching internet-facing servers. Audit all systems using Microsoft's Security Compliance Toolkit. Verify update installation with Get-Hotfix PowerShell commands. Report incidents to CISA's vulnerability reporting portal.