CVE-2026-83999: Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability
Improper link resolution before file access ('link following') in Windows Resilient File System (ReFS) Deduplication Service allows an authorized attacker to elevate privileges locally.
Other sources
Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.9445Patch KB5124008 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33438Patch KB5122871 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.28000.2954Patch KB5124012 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.9445Patch KB5124008
Event History
Frequently Asked Questions
Who can exploit this vulnerability?
An attacker must already be authorized on the affected system and able to act locally. The issue enables elevation of privilege rather than initial remote access.
Which systems are identified as affected?
The provided data identifies Microsoft Windows 11 and Microsoft Windows Server 2025. No specific editions, builds, or update levels are provided.
What access does an attacker need before exploitation?
The vector is local, user interaction is not required, and the attacker needs low privileges. Exploitation is rated as high complexity.