Actively exploited · Published Jul 14, 2026 · Assigned by microsoft
CVE-2026-56155Active Directory Federation Services Elevation of Privilege Vulnerability
High 7.8 Exploited
In plain English
A high-severity security flaw in Windows 10 Version 1607 from Microsoft. Attackers are actively exploiting it in the wild (listed by CISA on July 14, 2026). The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). 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.
CISA guidance
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.
Federal agencies must remediate by Jul 28, 2026.
Official description
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 Version 1607 | 10.0.14393.0 – before 10.0.14393.9339 |
| Microsoft | Windows 10 Version 1809 | 10.0.17763.0 – before 10.0.17763.9020 |
| Microsoft | Windows Server 2012 | 6.2.9200.0 – before 6.2.9200.26226 |
| Microsoft | Windows Server 2012 (Server Core installation) | 6.2.9200.0 – before 6.2.9200.26226 |
| Microsoft | Windows Server 2012 R2 | 6.3.9600.0 – before 6.3.9600.23291 |
| Microsoft | Windows Server 2012 R2 (Server Core installation) | 6.3.9600.0 – before 6.3.9600.23291 |
| Microsoft | Windows Server 2016 | 10.0.14393.0 – before 10.0.14393.9339 |
| Microsoft | Windows Server 2016 (Server Core installation) | 10.0.14393.0 – before 10.0.14393.9339 |
| Microsoft | Windows Server 2019 | 10.0.17763.0 – before 10.0.17763.9020 |
| Microsoft | Windows Server 2019 (Server Core installation) | 10.0.17763.0 – before 10.0.17763.9020 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – before 10.0.20348.5386 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.33158 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.33158 |
Weakness: CWE-1220 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
References
- Active Directory Federation Services Elevation of Privilege Vulnerability vendor-advisory, patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56155 government-resource