A high-severity use after free vulnerability in Windows Kernel-Mode Drivers permits local attackers to escalate their privileges to administrative levels.

This is a use after free flaw (CWE-416) within the kernel-mode driver subsystem. An attacker who has already gained low-privileged access to the system can trigger this condition to execute arbitrary code with kernel-level privileges.

The successful exploitation of this vulnerability poses a severe risk to organizational security, as it allows a standard user to bypass security controls and gain full control over the operating system. With a CVSS score of 7.8, this flaw represents a significant risk for lateral movement, data theft, and persistent malware installation within the environment.

Immediate Action: Apply the relevant security updates provided in the Microsoft Security Update Guide for CVE-2026-20859 to all affected Windows systems.

Proactive Monitoring: Monitor system logs for unexpected kernel crashes or abnormal process behavior that may indicate an attempt to exploit memory corruption vulnerabilities.

Compensating Controls: Ensure that endpoint detection and response (EDR) solutions are active and configured to detect unauthorized privilege escalation attempts.

Public Exploit Available: No

Given the ability for an attacker to escalate privileges to the kernel level, this vulnerability should be treated with high urgency. IT administrators must prioritize the deployment of the vendor-supplied patches across all affected Windows 11 and Windows Server 2025 instances to prevent potential local privilege escalation attacks.