This vulnerability (CVE-2026-20857) is classified as CWE-822 (Untrusted Pointer Dereference) and affects Windows 10 Version 1809 (build 10.0.17763.0). It exists in the Windows Cloud Files Mini Filter Driver and enables a local attacker with some level of authorization to escalate privileges. The CVSS v3.1 base score is 7.8, indicating high severity, with attack vector local, low attack complexity, and no user interaction required. Microsoft has published an official fix for this vulnerability.

Successful exploitation allows an authorized local attacker to elevate their privileges, potentially gaining higher system rights and control. The confidentiality, integrity, and availability impacts are all rated high according to the CVSS vector, meaning the attacker could fully compromise the affected system.

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-2026-20857 to remediate this vulnerability.