CVE-2026-83999 Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability
An authorized local attacker can exploit improper link resolution in the Windows ReFS Deduplication Service to elevate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-83999?
CVE-2026-83999 is a high-severity path traversal vulnerability in Microsoft Windows 11 24h2, published on 8 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Improper link resolution before file access ('link following') in Windows Resilient File System (ReFS) Deduplication Service allows an authorized attacker to elevate privileges locally.
Weakness: CWE-59
Which versions are affected by CVE-2026-83999?
It affects 4 products.
Products include Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows Server 2025.
How do I fix CVE-2026-83999?
No fix has been published for CVE-2026-83999 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-83999 being exploited?
There is no known exploitation of CVE-2026-83999 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 11 24h2
- CVE-2025-60710 Microsoft Windows Link Following
- CVE-2026-54990 Remote Desktop Client Remote Code Execution Vulnerability
- CVE-2025-50165 Windows Graphics Component Remote Code Execution Vulnerability
- CVE-2025-21311 Windows NTLM V1 Elevation of Privilege Vulnerability
- CVE-2026-108463 Windows SmartScreen Security Feature Bypass Vulnerability
Sources
Also known as GHSA-wwcf-37pw-hpqr.