CISA KEV · Known exploitedHigh

CVE-2026-56155

Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows Server 2012

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

CVSS
7.8
EPSS
0.38%
30.3% percentile
CISA KEV
Listed
Published
2026.07.15
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability0.38%
Technical severityCVSS 7.8

Vulnerability overview

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

Affected product and versions

Product
Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows Server 2012
Affected versions
>= 10.0.14393.0 < 10.0.14393.9339, >= 10.0.17763.0 < 10.0.17763.9020, >= 6.2.9200.0 < 6.2.9200.26226, >= 6.3.9600.0 < 6.3.9600.23291, >= 10.0.20348.0 < 10.0.20348.5386, >= 10.0.26100.0 < 10.0.26100.33158, < 10.0.14393.9339, < 10.0.17763.9020, r2, < 10.0.20348.5386, < 10.0.26100.33158
Fixed versions
10.0.14393.9339, 10.0.17763.9020, 10.0.20348.5386, 10.0.26100.33158

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA 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.

Due date: 2026.07.28
  1. 1
    Identify

    Confirm that Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows Server 2012 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-1220
KEV added
2026.07.14
Ransomware use
미확인
CVE-2026-56155 — Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows Server 2012 | SECUFOCUS NOW