CVE-2026-103576: Active Directory Federation Services (AD FS) Spoofing Vulnerability

Overview

Severity

Medium (CVSS 6.5)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Category

Spoofing

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Oct

Released

2026-10-13

Description

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

FAQ

According to the CVSS metric, successful exploitation of this vulnerability could lead to loss of confidentiality (C:H)? What does that mean for this vulnerability? Successful exploitation of this vulnerability allows an attacker to impersonate another user and access information based on the victim user's permission levels.

Affected Products (12)

Windows

• Windows Server 2016
• Windows Server 2016 (Server Core installation)
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows Server 2025
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 1607 for 32-bit Systems
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 1809 for x64-based Systems

Security Updates (4)

• 5126868
• 5126651
• 5126655
• 5126646

Revision History

• 2026-10-13: Information published.