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CVE-2026-56155

High 7.8 Exploited in the wild (KEV)

Confirmed active exploitation — CISA KEV catalog

Name
Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability
Added to catalog
Remediation due date (US federal)
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.

Description

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

Metrics

CVSS 3.1
7.8 (HIGH) Score source: CNA CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS — exploit probability
0% (percentile: 28) as of 1 November 2026
CWE
CWE-1220

Affected products

microsoft: windows 10 1607; microsoft: windows 10 1809; microsoft: windows server 2012; microsoft: windows server 2016; microsoft: windows server 2019; microsoft: windows server 2022; microsoft: windows server 2025

References