CVE-2026-55001: Active Directory Domain Services Elevation of Privilege Vulnerability

Severity: high (CVSS 7.8 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: 2026-07-14 · updated 2026-10-28
Weakness: CWE-295

Description

Improper certificate validation in Windows Active Directory allows an authorized attacker to elevate privileges locally.

Affected products

Microsoft Windows 10 1607: before 10.0.14393.9339 — fixed in 10.0.14393.9339
Microsoft Windows 10: before 10.0.17763.9020 — fixed in 10.0.17763.9020
Microsoft Windows Server 2016: before 10.0.14393.9339 — fixed in 10.0.14393.9339
Microsoft Windows Server 2019: before 10.0.17763.9020 — fixed in 10.0.17763.9020
Microsoft Windows Server 2022: before 10.0.20348.5386 — fixed in 10.0.20348.5386
Microsoft Windows Server 2025: before 10.0.26100.33158 — fixed in 10.0.26100.33158
Microsoft Windows 10 1607: from 10.0.14393.0 before 10.0.14393.9339 — fixed in 10.0.14393.9339
Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.9020 — fixed in 10.0.17763.9020
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.9339 — fixed in 10.0.14393.9339
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.9020 — fixed in 10.0.17763.9020
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.5386 — fixed in 10.0.20348.5386
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.33158 — fixed in 10.0.26100.33158

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1607 10.0.14393.9339; Microsoft Windows 10 10.0.17763.9020; Microsoft Windows Server 2016 10.0.14393.9339; Microsoft Windows Server 2019 10.0.17763.9020; Microsoft Windows Server 2022 10.0.20348.5386; Microsoft Windows Server 2025 10.0.26100.33158; Microsoft Windows 10 1607 10.0.14393.9339; Microsoft Windows 10 10.0.17763.9020; Microsoft Windows Server 2016 10.0.14393.9339; Microsoft Windows Server 2019 10.0.17763.9020; Microsoft Windows Server 2022 10.0.20348.5386; Microsoft Windows Server 2025 10.0.26100.33158. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55001

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