CVE-2026-56155
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Exploited in the wild
This vulnerability is on the CISA Known Exploited Vulnerabilities list, added 2026-07-14. Federal due date: 2026-07-28.
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Impact
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Microsoft | Windows 10 1607 | before 10.0.14393.9339 |
| Microsoft | Windows 10 1809 | before 10.0.17763.9020 |
| Microsoft | Windows Server 2012 | All versions Version r2 |
| Microsoft | Windows Server 2016 | before 10.0.14393.9339 |
| Microsoft | Windows Server 2019 | before 10.0.17763.9020 |
| Microsoft | Windows Server 2022 | before 10.0.20348.5386 |
| Microsoft | Windows Server 2025 | before 10.0.26100.33158 |
| Microsoft | Windows 10 Version 1607 | from 10.0.14393.0 before 10.0.14393.9339 |
| Microsoft | Windows 10 Version 1809 | from 10.0.17763.0 before 10.0.17763.9020 |
| Microsoft | Windows Server 2012 | from 6.2.9200.0 before 6.2.9200.26226 |
| Microsoft | Windows Server 2012 (Server Core Installation) | from 6.2.9200.0 before 6.2.9200.26226 |
| Microsoft | Windows Server 2012 R2 | from 6.3.9600.0 before 6.3.9600.23291 |
| Microsoft | Windows Server 2012 R2 (Server Core Installation) | from 6.3.9600.0 before 6.3.9600.23291 |
| Microsoft | Windows Server 2016 | from 10.0.14393.0 before 10.0.14393.9339 |
| Microsoft | Windows Server 2016 (Server Core Installation) | from 10.0.14393.0 before 10.0.14393.9339 |
| Microsoft | Windows Server 2019 | from 10.0.17763.0 before 10.0.17763.9020 |
| Microsoft | Windows Server 2019 (Server Core Installation) | from 10.0.17763.0 before 10.0.17763.9020 |
| Microsoft | Windows Server 2022 | from 10.0.20348.0 before 10.0.20348.5386 |
| Microsoft | Windows Server 2025 | from 10.0.26100.0 before 10.0.26100.33158 |
| Microsoft | Windows Server 2025 (Server Core Installation) | from 10.0.26100.0 before 10.0.26100.33158 |