CVE intelligenceCISA KEV

CVE-2026-56155

Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability

Published Jul 14, 2026Sources checked Nov 12, 2026

7.8HIGHCVSS out of 10

What this means

Actively exploited

CISA lists CVE-2026-56155 in its Known Exploited Vulnerabilities catalog, which means exploitation has been observed. The entry applies to Microsoft Active Directory Federation Services.

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.

Public exploit: Not collected.

Microsoft Security Response Center: Exploitation reported by Microsoft Security Response Center (2026-07-14)
Microsoft exploitation status: Exploited:Yes

What to do next

Remediation and response

Review the linked vendor advisory and apply the mitigation or fixed release for your affected product.

Microsoft Security Response Center guidance

Vendor revision: Jul 14, 2026

Vendor remediation details

Install KB5099538. Install KB5099540. Install KB5099536. Install KB5099535. Install KB5099445. Install KB5099444.

Vendor-listed releases

10.0.17763.9020
10.0.20348.5386
10.0.26100.33158
10.0.14393.9339
6.2.9200.26226
6.3.9600.23291

CISA KEVListedObserved exploitation

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors1Source-linked actor relationships

Overview

What is CVE-2026-56155?

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

Source: NVD

Reported activity: Microsoft exploitation status: Exploited:Yes
Microsoft Security Response Center · Published Jul 14, 2026

CISA says: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 catalog due date Jul 28, 2026