CVE-2026-77503: CWE-125: Out-of-bounds Read in Microsoft Windows 10 Version 1607

CVE-2026-77503 is an out-of-bounds read vulnerability (CWE-125) in the Windows NTFS file system driver that enables a local attacker without privileges to elevate their privileges on the system. The vulnerability affects various builds of Windows 10 Version 1607 and related versions, with affected versions ranging from 10.0.14393.0 up to but not including 10.0.14393.9512 and other specified build ranges. The CVSS v3.1 base score is 8.4, indicating high severity with impact on confidentiality, integrity, and availability. Microsoft has released an official fix for this vulnerability as documented in their security update guide.

Successful exploitation of this vulnerability allows an unauthorized local attacker to elevate privileges, potentially gaining higher-level access to the system. This can lead to full system compromise affecting confidentiality, integrity, and availability of the affected Windows 10 systems.

An official fix is available from Microsoft. Users and administrators should apply the security updates provided by Microsoft for the affected Windows 10 versions as detailed in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77503. No additional mitigation steps are indicated beyond applying the official patch.