CVE-2026-83586 Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability
Weak authentication in the Windows ReFS Deduplication Service allows local attackers 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-2026-83586?
CVE-2026-83586 is a high-severity authentication bypass vulnerability in Microsoft Windows 11 23h2, published on 13 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Weak authentication in Windows Resilient File System (ReFS) Deduplication Service allows an authorized attacker to elevate privileges locally.
Weakness: CWE-1390
Which versions are affected by CVE-2026-83586?
It affects 6 products.
Products include Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows 11 26h2, Microsoft Windows Server 2025.
How do I fix CVE-2026-83586?
No fix has been published for CVE-2026-83586 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-83586 being exploited?
There is no known exploitation of CVE-2026-83586 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 11 23h2
- CVE-2026-81963 Microsoft Windows Link Following
- CVE-2026-100219 Microsoft QUIC Remote Code Execution Vulnerability
- CVE-2026-96909 Windows BitLocker Remote Code Execution Vulnerability
- CVE-2026-62815 Microsoft QUIC Remote Code Execution Vulnerability
- CVE-2026-45657 Windows Kernel Remote Code Execution Vulnerability
Sources
Also known as GHSA-xxw2-8m5q-m3r2.