MSRC-CVE-2026-56155 — Active Directory Federation Services Elevation of Privilege Vulnerability

Summary

Impact: Elevation of Privilege. Microsoft rating: Important. Exploited according to Microsoft — Exploitation Detected. Customer action: Required.

Details

What privileges could be gained by an attacker who successfully exploited the vulnerability?
An attacker who successfully exploited this vulnerability could gain administrator privileges.

Security updates
10.0.17763.9020 — https://support.microsoft.com/help/5099538
10.0.20348.5386 — https://support.microsoft.com/help/5099540
10.0.26100.33158 — https://support.microsoft.com/help/5099536
10.0.14393.9339 — https://support.microsoft.com/help/5099535
6.2.9200.26226 — https://support.microsoft.com/help/5099445
6.3.9600.23291 — https://support.microsoft.com/help/5099444

Vulnerabilities 1

High 7.8

CVE-2026-56155 Exploited

Active Directory Federation Services Elevation of Privilege Vulnerability

Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.

Microsoft Windows Server 2019 Windows Server 2019 (Server Core installation) Windows 10 Version 1809 Windows

Jul 14, 2026
KEV Jul 14, 2026

Revision history

2026-07-14 #1
Information published.

References

CVE-2026-56155 Active Directory Federation Services Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56155
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
Common Vulnerability Scoring System
https://www.first.org/cvss