Actively exploited · Published Jul 14, 2026 · Assigned by microsoft

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

High 7.8 Exploited

In plain English

A high-severity security flaw in Windows 10 Version 1607 from Microsoft. Attackers are actively exploiting it in the wild (listed by CISA on July 14, 2026). The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). 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.

Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.3%top 71.7% of all CVEs
Exploited in the wildYesCISA KEV since Jul 14, 2026
Attack toolingNoneno public tooling known

CISA guidance

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.

Federal agencies must remediate by Jul 28, 2026.

Official description

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

Affected products (as reported)

VendorProductVersions
Microsoft Windows 10 Version 1607 10.0.14393.0 – before 10.0.14393.9339
Microsoft Windows 10 Version 1809 10.0.17763.0 – before 10.0.17763.9020
Microsoft Windows Server 2012 6.2.9200.0 – before 6.2.9200.26226
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.0 – before 6.2.9200.26226
Microsoft Windows Server 2012 R2 6.3.9600.0 – before 6.3.9600.23291
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 – before 6.3.9600.23291
Microsoft Windows Server 2016 10.0.14393.0 – before 10.0.14393.9339
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.0 – before 10.0.14393.9339
Microsoft Windows Server 2019 10.0.17763.0 – before 10.0.17763.9020
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0 – before 10.0.17763.9020
Microsoft Windows Server 2022 10.0.20348.0 – before 10.0.20348.5386
Microsoft Windows Server 2025 10.0.26100.0 – before 10.0.26100.33158
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0 – before 10.0.26100.33158

Weakness: CWE-1220 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

References