Heap-based buffer overflow in Microsoft Windows and Windows Server - CVE-2026-108399
Published: October 13, 2026
Vulnerability identifier: #VU154364
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-108399
CWE-ID: CWE-122
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local privileged user to escalate privileges on the host system beyond the guest virtual machine boundary.
The vulnerability exists due to a heap-based buffer overflow in Windows Hyper-V when operating locally. A local privileged user can exploit the overflow to escalate privileges on the host system beyond the guest virtual machine boundary.
User interaction is required. Successful exploitation requires a deep understanding of the system and may depend on the environment, system configuration, and additional security measures.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-108399
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7807, 10 1607 10.0.14393.9612, 10 1809 10.0.17763.9376, 11 23H2 10.0.22631.7652, 11 24H2 10.0.26100.9711, 11 25H2 10.0.26200.9711, 11 26H1 10.0.28000.3231
Windows Server - addressed in versions 2012 R2 6.3.9600.23470, 2012 6.2.9200.26434, 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650
Windows Server - addressed in versions 2012 R2 6.3.9600.23470, 2012 6.2.9200.26434, 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650