Time-of-check Time-of-use (TOCTOU) Race Condition in Windows and Windows Server - CVE-2026-56648
Published: July 17, 2026
Vulnerability identifier: #VU138125
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-56648
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
The vulnerability allows a remote user to elevate privileges.
The vulnerability exists due to a time-of-check time-of-use race condition in Windows Network File System when handling network file system operations. A remote user can trigger the race condition to elevate privileges.
Successful exploitation requires winning a race condition and may result in SYSTEM privileges.
How to mitigate CVE-2026-56648
Install security update from vendor's website.