CVE-2026-56155MicrosoftServers and softwareJuly 14, 2026

Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability

High 7.8Actively exploited

Description

Microsoft Active Directory Federation Services contains an insufficient granularity of access control vulnerability that allows an authorized attacker to elevate privileges locally.

What to do

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.

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Details

Vendor
Microsoft
Product
Active Directory Federation Services
CVE
CVE-2026-56155
Affected versions
Windows 10 Version 1607 10.0: from 10.0.14393.0 to 10.0.14393.9339 (excluded) — fixed in 10.0.14393.9339
Windows 10 Version 1809 10.0: from 10.0.17763.0 to 10.0.17763.9020 (excluded) — fixed in 10.0.17763.9020
Windows Server 2012 6.2: from 6.2.9200.0 to 6.2.9200.26226 (excluded) — fixed in 6.2.9200.26226
Windows Server 2012 (Server Core installation) 6.2: from 6.2.9200.0 to 6.2.9200.26226 (excluded) — fixed in 6.2.9200.26226
Windows Server 2012 R2 6.3: from 6.3.9600.0 to 6.3.9600.23291 (excluded) — fixed in 6.3.9600.23291
Windows Server 2012 R2 (Server Core installation) 6.3: from 6.3.9600.0 to 6.3.9600.23291 (excluded) — fixed in 6.3.9600.23291
Windows Server 2016 10.0: from 10.0.14393.0 to 10.0.14393.9339 (excluded) — fixed in 10.0.14393.9339
Windows Server 2016 (Server Core installation) 10.0: from 10.0.14393.0 to 10.0.14393.9339 (excluded) — fixed in 10.0.14393.9339
Windows Server 2019 10.0: from 10.0.17763.0 to 10.0.17763.9020 (excluded) — fixed in 10.0.17763.9020
Windows Server 2019 (Server Core installation) 10.0: from 10.0.17763.0 to 10.0.17763.9020 (excluded) — fixed in 10.0.17763.9020
Windows Server 2022 10.0: from 10.0.20348.0 to 10.0.20348.5386 (excluded) — fixed in 10.0.20348.5386
Windows Server 2025 10.0: from 10.0.26100.0 to 10.0.26100.33158 (excluded) — fixed in 10.0.26100.33158
Windows Server 2025 (Server Core installation) 10.0: from 10.0.26100.0 to 10.0.26100.33158 (excluded) — fixed in 10.0.26100.33158 (from the advisory and NVD; check the exact builds in the official advisory)
CVSS score
7.8
Actively exploited
Yes, listed in the CISA Known Exploited Vulnerabilities catalog
CISA due date
July 28, 2026 (deadline for US federal agencies: a good benchmark for you too)
Source
CISA KEV – original advisory
Published
July 14, 2026

The description and the recommended action are quoted from the public advisory; severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.

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