7.8
High
Exploited
CVE-2026-56155 Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability
Active exploitation observed
· CISA KEV catalogue
Required action
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.
Ransomware campaigns
Not observed so far
Weakness
CWE-1220
Description
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Windows 10 Version 1607 10.0 | 10.0.14393.0 → < 10.0.14393.9339 | 10.0.14393.9339 |
| Windows 10 Version 1809 10.0 | 10.0.17763.0 → < 10.0.17763.9020 | 10.0.17763.9020 |
| Windows Server 2012 6.2 | 6.2.9200.0 → < 6.2.9200.26226 | 6.2.9200.26226 |
| Windows Server 2012 (Server Core installation) 6.2 | 6.2.9200.0 → < 6.2.9200.26226 | 6.2.9200.26226 |
| Windows Server 2012 R2 6.3 | 6.3.9600.0 → < 6.3.9600.23291 | 6.3.9600.23291 |
| Windows Server 2012 R2 (Server Core installation) 6.3 | 6.3.9600.0 → < 6.3.9600.23291 | 6.3.9600.23291 |
| Windows Server 2016 10.0 | 10.0.14393.0 → < 10.0.14393.9339 | 10.0.14393.9339 |
| Windows Server 2016 (Server Core installation) 10.0 | 10.0.14393.0 → < 10.0.14393.9339 | 10.0.14393.9339 |
| Windows Server 2019 10.0 | 10.0.17763.0 → < 10.0.17763.9020 | 10.0.17763.9020 |
Show the 4 other branches Hide the 4 other branches
| Product | Affected versions | Fixed in |
|---|---|---|
| Windows Server 2019 (Server Core installation) 10.0 | 10.0.17763.0 → < 10.0.17763.9020 | 10.0.17763.9020 |
| Windows Server 2022 10.0 | 10.0.20348.0 → < 10.0.20348.5386 | 10.0.20348.5386 |
| Windows Server 2025 10.0 | 10.0.26100.0 → < 10.0.26100.33158 | 10.0.26100.33158 |
| Windows Server 2025 (Server Core installation) 10.0 | 10.0.26100.0 → < 10.0.26100.33158 | 10.0.26100.33158 |
References
- Active Directory Federation Services Elevation of Privilege Vulnerability msrc.microsoft.com
Timeline
- Published
- Added to the KEV catalogue
- Last modified
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