Auth bypass in Microsoft Windows 10 Version 21h2
CVE-2026-83656
Missing authentication for critical function in Windows Modern Device Management (MDM) allows an authorized attacker to perform tampering locally.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Microsoft Windows 10 Version 21h2
- Microsoft Windows 10 Version 22h2
- Microsoft Windows 11 Version 23h2
- Microsoft Windows 11 Version 24h2
- Microsoft Windows 11 Version 25h2
- Microsoft Windows 11 Version 26h1
- Microsoft Windows 11 Version 26h2
- Microsoft Windows Server 2022
- Microsoft Windows Server 2025
- Microsoft Windows Server 2025 (Server Core Installation)
Weakness classification (CWE)
References
- Windows Modern Device Management (MDM) Tampering Vulnerability (vendor-advisory, patch)
Frequently asked questions
- What is CVE-2026-83656?
- CVE-2026-83656 is a medium-severity vulnerability in Microsoft Windows 10 Version 21h2, classified under Missing Authentication for Critical Function. CVSS score: 4.7/10. Published 2026-10-13.
- How severe is CVE-2026-83656?
- Medium severity. CVSS v3 base score is 4.7 out of 10.