CVE-2026-70005: Active Directory Federation Services (AD FS) Security Feature Bypass Vulnerability

Overview

Severity

Medium (CVSS 5.9)

CVSS Vector

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

Category

Security Feature Bypass

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Oct

Released

2026-10-13

Description

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

FAQ

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? A high attack complexity means that successful exploitation is complex and time‑consuming, requiring significant effort and precise conditions for an attacker to reliably exploit the vulnerability.

Affected Products (6)

Windows

• 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)

Security Updates (3)

• 5126651
• 5126655
• 5126646

Revision History

• 2026-10-13: Information published.