Time-of-check Time-of-use (TOCTOU) Race Condition in Microsoft Windows and Windows Server - CVE-2026-56648
Published: July 17, 2026
Vulnerability identifier: #VU138125
CSH Severity: Low
CVSS v4: 7.7 [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]
CVE-ID: CVE-2026-56648
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
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.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-56648
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7548, 10 22H2 10.0.19045.7548, 10 1607 10.0.14393.9339, 10 1809 10.0.17763.9020, 11 24H2 10.0.26100.8875, 11 26H1 10.0.28000.2525
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158