Heap-based buffer overflow in Microsoft Windows and Windows Server - CVE-2026-20876
Published: January 13, 2026
Vulnerability identifier: #VU121248
CSH Severity: Low
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-20876
CWE-ID: CWE-122
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to escalate privileges on the target system.
The vulnerability exists due to a boundary error in Windows Virtualization-Based Security (VBS) Enclave. A local administrator can pass specially crafted data to the application, trigger a heap-based buffer overflow and gain elevated privileges on the target system.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-20876
Install updates from vendor's website.
Microsoft Windows - addressed in versions 10 1607 10.0.14393.8783, 11 23H2 10.0.22631.6491, 11 24H2 10.0.26100.7623
Windows Server - addressed in versions 2022 23H2 10.0.25398.2092, 2025 10.0.26100.7623, 2025 10.0.26100.32230
Windows Server - addressed in versions 2022 23H2 10.0.25398.2092, 2025 10.0.26100.7623, 2025 10.0.26100.32230