A null pointer dereference vulnerability in the Windows Ancillary Function Driver for WinSock allows an authorized local attacker to elevate their privileges to a higher level.

This vulnerability is a null pointer dereference (CWE-476) within the Windows Ancillary Function Driver for WinSock. The flaw requires the attacker to have at least low-level authenticated access to the system to trigger the dereference and escalate privileges.

Successful exploitation allows an authorized user to gain elevated privileges on the host system, potentially leading to full system compromise. With a CVSS score of 7.8, this high-severity vulnerability poses a significant risk to the confidentiality, integrity, and availability of sensitive data managed by the affected systems.

Immediate Action: Apply the official security updates provided by Microsoft in the March 2026 patch cycle to all affected Windows versions.

Proactive Monitoring: Monitor system logs for unusual process execution patterns or attempts to interact with the Ancillary Function Driver for WinSock that may indicate exploitation attempts.

Compensating Controls: Ensure that the principle of least privilege is strictly enforced across the environment to limit the number of users who possess the necessary local access to attempt this exploit.

Public Exploit Available: No (exploit_available unknown).

Given the potential for complete system compromise, IT administrators should prioritize the deployment of the relevant security updates across the fleet. Testing the patch in a development environment prior to enterprise-wide rollout is recommended to ensure stability, but the high severity necessitates a rapid response.