Stack-based buffer overflow in Windows and Windows Server - CVE-2026-40399
Published: May 12, 2026
Vulnerability identifier: #VU131279
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-40399
CWE-ID: CWE-121
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
The vulnerability allows a local user to escalate privileges on the target system.
The vulnerability exists due to a boundary error in Windows TCP/IP. A local user can trigger stack-based buffer overflow and gain elevated privileges on the target system.
How to mitigate CVE-2026-40399
Install updates from vendor's website.