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

CVE-2026-69617 is fixed in 4 products on 1 platform, first by KB5124012, released September 8, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-69617
- Priority: High
- CVSS: 7.0 (Important)
- EPSS: 0.0026
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Unlikely
- Published: Sep 8, 2026
- Weakness: Out-of-bounds Read
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69617

## Description

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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Windows 11 Version 26H1 for ARM64-based Systems | 28000.2954 | [KB5124012](https://patchblox.com/security/data/fix/microsoft/kb5124012.md) | Sep 8, 2026 |
| Microsoft | Windows 11 version 26H1 for x64-based Systems | 28000.2954 | [KB5124012](https://patchblox.com/security/data/fix/microsoft/kb5124012.md) | Sep 8, 2026 |
| Microsoft | Windows Server 2025 | 26100.33438 | [KB5122871](https://patchblox.com/security/data/fix/microsoft/kb5122871.md) | Sep 8, 2026 |
| Microsoft | Windows Server 2025 (Server Core installation) | 26100.33438 | [KB5122871](https://patchblox.com/security/data/fix/microsoft/kb5122871.md) | Sep 8, 2026 |

---

Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.