CVE-2026-69617
High CVSS 7Published 2026-09-08 ยท last changed 2026-09-09
The fix
Microsoft fixes this in updatesKB5124012, KB5122871. The fixed build differs per Windows version, so the row that matters is the one matching the machine you are looking at.
| Windows version | Fixed in build | Update | Released |
|---|---|---|---|
| Windows 11 Version 26H1 for ARM64-based Systems | 10.0.28000.2954 | KB5124012 | 2026-09-20 |
| Windows 11 version 26H1 for x64-based Systems | 10.0.28000.2954 | KB5124012 | 2026-09-20 |
| Windows Server 2025 | 10.0.26100.33438 | KB5122871 | 2026-09-20 |
| Windows Server 2025 (Server Core installation) | 10.0.26100.33438 | KB5122871 | 2026-09-20 |
Having the KB is not the same as knowing whether a machine has it. Windows updates supersede each other, so the update you installed often covers a fix that shipped in an earlier one. Paste your build into the patch checker and it walks that chain for you.
What it is
Out-of-bounds read in Windows Resilient File System (ReFS) allows an authorized attacker to elevate privileges locally.
Sources
CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H