Improper Validation of Syntactic Correctness of Input in Microsoft Windows and Windows Server - CVE-2026-83728
Published: October 14, 2026
Vulnerability identifier: #VU154901
CSH Severity: Low
CVSS v4: 8.5 [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]
CVE-ID: CVE-2026-83728
CWE-ID: CWE-1286
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to bypass MAC-address spoofing protections and impersonate another network endpoint, potentially enabling interception, modification, or disruption of network traffic.
The vulnerability exists due to improper validation of syntactic correctness of input in the Windows Hyper-V Virtual Switch when processing network packets. A local user can send a specially crafted network packet through the virtual switch to bypass MAC-address spoofing protections and impersonate another network endpoint, potentially enabling interception, modification, or disruption of network traffic.
Exploitation requires running code in a Hyper-V guest. User interaction is not required.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-83728
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