Main Vulnerability Database Vulnerabilities #VU148348

Link following in Microsoft Windows and Windows Server - CVE-2026-83999

Published: September 9, 2026

Vulnerability identifier: #VU148348

CSH Severity: Low

CVSS v4: 7.3 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-83999

CWE-ID: CWE-59

Exploitation vector: Local access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to escalate privileges.

The vulnerability exists due to improper link resolution before file access (\'link following\') in the Windows Resilient File System (ReFS) Deduplication Service when accessing files. A local user can win a race condition to escalate privileges.

Successful exploitation could grant SYSTEM privileges.

Affected software

Microsoft Windows
Windows Server

How to mitigate CVE-2026-83999

Install security update from vendor's website.

Microsoft Windows - addressed in versions 11 24H2 10.0.26100.9445, 11 25H2 10.0.26200.9445, 11 26H1 10.0.28000.2954
Windows Server - update to 2025 10.0.26100.33438

External References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-83999

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