CVE-2026-83586: Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability
Weak authentication 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 10.0.26100.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.22631.7652Patch KB5126653 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33650Patch KB5126646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.28000.3231Patch KB5127646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26300.9711Patch KB5127648
Event History
Frequently Asked Questions
Which environments should be prioritized for review?
Prioritize systems running Microsoft Windows 11 or Microsoft Windows Server 2025 where the Microsoft Windows Resilient File System (ReFS) Deduplication Service is present.
What level of access does an attacker need?
Exploitation requires an attacker to already be authorized on the affected system and able to act locally. The supplied vector indicates no user interaction is required.