CVE-2026-83657: Windows Modern Device Management (MDM) Tampering Vulnerability

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-31
Weakness: CWE-1390

Description

Weak authentication in Windows Modern Device Management (MDM) allows an authorized attacker to perform tampering locally.

Affected products

Microsoft Windows 10: before 10.0.17763.9376 — fixed in 10.0.17763.9376
Microsoft Windows Server 2019: before 10.0.17763.9376 — fixed in 10.0.17763.9376
Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.9376 — fixed in 10.0.17763.9376
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.9376 — fixed in 10.0.17763.9376

How to fix

Upgrade to a fixed version: Microsoft Windows 10 10.0.17763.9376; Microsoft Windows Server 2019 10.0.17763.9376; Microsoft Windows 10 10.0.17763.9376; Microsoft Windows Server 2019 10.0.17763.9376. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83657

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