CVE-2026-69617: Windows Resilient File System (ReFS) Elevation of Privilege Vulnerability

Overview

Severity

High (CVSS 7)

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Category

Elevation of Privilege

Exploit Status

Not Exploited

Exploitation Likelihood

Unlikely

Patch Tuesday

2026-Sep

Released

2026-09-08

Description

Out-of-bounds read in Windows Resilient File System (ReFS) allows an authorized attacker to elevate privileges locally.

FAQ

What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges. According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation of this vulnerability requires an attacker to have a deep understanding of the system. Successful exploitation is not guaranteed and depends on a combination of factors that might include the environment, system configuration, and the presence of additional security measures.

Affected Products (4)

Windows

• Windows Server 2025 (Server Core installation)
• Windows Server 2025
• Windows 11 version 26H1 for x64-based Systems
• Windows 11 Version 26H1 for ARM64-based Systems

Security Updates (2)

• 5122871
• 5124012

Acknowledgments

Thanatos Tian (HKPolyU) & wgg & @2st__ with Diffract

Revision History

• 2026-09-08: Information published.