Vulnerability · Published Oct 13, 2026 · Assigned by microsoft
CVE-2026-83586Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability
High 7.8
In plain English
A high-severity security flaw in Windows 11 version 23H2 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities).
Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.3%top 75.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Weak authentication in Windows Resilient File System (ReFS) Deduplication Service allows an authorized attacker to elevate privileges locally.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 – before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 – before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 – before 10.0.26100.9711 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 – before 10.0.26200.9711 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – before 10.0.28000.3231 |
| Microsoft | Windows 11 Version 26H2 | 10.0.26300.0 – before 10.0.26300.9711 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.33650 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.33650 |
Weakness: CWE-1390 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C