CVE-2026-83674

Active Directory Federation Services (AD FS) Spoofing Vulnerability

State: Published
Severity: 8.1 High
Published: Oct 13, 2026
Updated: Oct 31, 2026
Reserved: Aug 31, 2026

Description

Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.

Scores

CVSS	Score	Vector	Source
3.1	8.1 High	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-1390 Weak Authentication

Affected Products

Product	Versions
Windows 10 Version 1607Microsoft	10.0.14393.0 to before 10.0.14393.9612Affected
Windows 10 Version 1809Microsoft	10.0.17763.0 to before 10.0.17763.9376Affected
Windows Server 2016Microsoft	10.0.14393.0 to before 10.0.14393.9612Affected
Windows Server 2016 (Server Core installation)Microsoft	10.0.14393.0 to before 10.0.14393.9612Affected
Windows Server 2019Microsoft	10.0.17763.0 to before 10.0.17763.9376Affected
Windows Server 2019 (Server Core installation)Microsoft	10.0.17763.0 to before 10.0.17763.9376Affected
Windows Server 2022Microsoft	10.0.20348.0 to before 10.0.20348.5761Affected
Windows Server 2025Microsoft	10.0.26100.0 to before 10.0.26100.33650Affected
Windows Server 2025 (Server Core installation)Microsoft	10.0.26100.0 to before 10.0.26100.33650Affected

References

Active Directory Federation Services (AD FS) Spoofing Vulnerabilityvendor-advisorypatch

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