Critical Windows Kernel Flaw Exposes Systems to Remote Takeover (CVE-2025-71105)

Microsoft has disclosed a critical security vulnerability (CVE-2025-71105) affecting multiple Windows versions, enabling remote attackers to execute malicious code with kernel-level privileges. This flaw carries a CVSS v3.1 severity score of 9.8.

Affected products include:

• Windows 11 versions 21H2 through 23H2
• Windows 10 versions 21H1 through 22H2
• Windows Server 2022

Exploitation occurs when attackers send specially crafted network packets to vulnerable systems. Successful compromise grants full control over devices without user interaction. Attackers could install malware, create administrator accounts, or exfiltrate sensitive data.

Microsoft confirmed active exploitation attempts targeting enterprise networks. The vulnerability resides in the Windows TCP/IP stack's handling of IPv4 fragments. Improper memory allocation routines create exploitable heap corruption conditions. Security researchers discovered the flaw during routine protocol analysis.

Mitigation requirements:

1. Apply Microsoft's July 2025 Patch Tuesday updates immediately via Windows Update
2. Block inbound TCP ports 139 and 445 at network perimeter firewalls
3. Enable Windows Defender Exploit Protection for all enterprise endpoints

Unsupported Windows versions require upgrading to patched releases. Microsoft recommends prioritizing updates for internet-facing servers and critical workstations. Enterprise administrators should validate patch deployment using Microsoft Endpoint Configuration Manager.

Microsoft's advisory confirms no functional changes to patched systems. The vulnerability was privately reported through coordinated disclosure on June 15, 2025. Public disclosure occurred alongside the July security updates on July 9, 2025.

System administrators must treat this patch as urgent. Delaying implementation creates significant risk of network compromise. Monitor the Microsoft Security Update Guide for additional technical details.