CVE-2021-40456: Microsoft Windows Server

Medium severity, CVSS 5.3. EPSS: 2.3% chance of exploitation in the next 30 days.

Windows AD FS Security Feature Bypass Vulnerability

Affected products

• Microsoft Windows Server: version 20h2 only
• Microsoft Windows Server 2019: affected versions not specified
• Microsoft Windows Server 2022: any version

Published 2021-10-13. Last modified 2026-06-17.