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

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-08 · updated 2026-10-31
Weakness: CWE-125

Description

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

Affected products

Microsoft Windows 11 version 26H1: before 10.0.28000.2954 — fixed in 10.0.28000.2954
Microsoft Windows Server 2025: before 10.0.26100.33438 — fixed in 10.0.26100.33438
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.2954 — fixed in 10.0.28000.2954
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.33438 — fixed in 10.0.26100.33438

How to fix

Upgrade to a fixed version: Microsoft Windows 11 version 26H1 10.0.28000.2954; Microsoft Windows Server 2025 10.0.26100.33438; Microsoft Windows 11 version 26H1 10.0.28000.2954; Microsoft Windows Server 2025 10.0.26100.33438. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69617

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