CVE-2026-83646

Active Directory Federation Services (AD FS) Spoofing Vulnerability

CVE-2026-83646 is fixed in 12 products on 1 platform, first by KB5126868, released October 13, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

4.8

Important

Exploitation

None reported

Exploitation Unlikely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0037

31st percentile

<p>Url redirection to untrusted site ('open redirect') in Active Directory Federation Services (AD FS) allows an authorized attacker to perform spoofing over a network.</p>

Where it's fixed

Product	Fixed in	Fix	Released
Microsoft
Windows 10 Version 1607 for 32-bit Systems	14393.9612	KB5126868	Oct 13, 2026
Windows 10 Version 1607 for x64-based Systems	14393.9612	KB5126868	Oct 13, 2026
Windows 10 Version 1809 for 32-bit Systems	17763.9376	KB5126651	Oct 13, 2026
Windows 10 Version 1809 for x64-based Systems	17763.9376	KB5126651	Oct 13, 2026
Windows Server 2016	14393.9612	KB5126868	Oct 13, 2026
Windows Server 2016 (Server Core installation)	14393.9612	KB5126868	Oct 13, 2026
Windows Server 2019	17763.9376	KB5126651	Oct 13, 2026
Windows Server 2019 (Server Core installation)	17763.9376	KB5126651	Oct 13, 2026
Windows Server 2022	20348.5761	KB5126655	Oct 13, 2026
Windows Server 2022 (Server Core installation)	20348.5761	KB5126655	Oct 13, 2026
Windows Server 2025	26100.33650	KB5126646	Oct 13, 2026
Windows Server 2025 (Server Core installation)	26100.33650	KB5126646	Oct 13, 2026

Details

Published
October 13, 2026
Weakness
URL Redirection to Untrusted Site ('Open Redirect')
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83646

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