This vulnerability (CVE-2026-21238) affects Windows 10 Version 1607 (build 10.0.14393.0) and is classified under CWE-284 (Improper Access Control). It resides in the Windows Ancillary Function Driver for WinSock, where insufficient access control enables an authorized local user to elevate their privileges. The CVSS 3.1 base score is 7.8, reflecting high severity with local attack vector, low attack complexity, and no user interaction required. Microsoft has published an official fix for this vulnerability as documented in their security update guide.

Successful exploitation allows an authorized local attacker to elevate privileges, potentially gaining full control over the affected system. This can lead to compromise of confidentiality, integrity, and availability of the system. There are no reports of active exploitation in the wild.

An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21238 to remediate this vulnerability. No additional mitigation steps are indicated by the vendor.