---
id: CVE-2026-56155
title: Active Directory Federation Services Elevation of Privilege Vulnerability
summary: >-
  Insufficient granularity of access control in Active Directory Federation
  Services (AD FS) allows an authorized attacker to elevate privileges locally.
severity: high
cvss: 7.8
cvssVector: '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'
cvssSource: cna
cwe:
  - CWE-1220
vendor: Microsoft
product: Windows 10 Version 1607
affected:
  - windows_10_version_1607 >= 10.0.14393.0 < 10.0.14393.9339
  - windows_10_version_1809 >= 10.0.17763.0 < 10.0.17763.9020
  - windows_server_2012 >= 6.2.9200.0 < 6.2.9200.26226
  - windows_server_2012_server_core_installation >= 6.2.9200.0 < 6.2.9200.26226
  - windows_server_2012_r2 >= 6.3.9600.0 < 6.3.9600.23291
  - >-
    windows_server_2012_r2_server_core_installation >= 6.3.9600.0 <
    6.3.9600.23291
  - windows_server_2016 >= 10.0.14393.0 < 10.0.14393.9339
  - >-
    windows_server_2016_server_core_installation >= 10.0.14393.0 <
    10.0.14393.9339
  - windows_server_2019 >= 10.0.17763.0 < 10.0.17763.9020
  - >-
    windows_server_2019_server_core_installation >= 10.0.17763.0 <
    10.0.17763.9020
  - windows_server_2022 >= 10.0.20348.0 < 10.0.20348.5386
  - windows_server_2025 >= 10.0.26100.0 < 10.0.26100.33158
  - >-
    windows_server_2025_server_core_installation >= 10.0.26100.0 <
    10.0.26100.33158
ssvc:
  exploitation: active
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-15T03:55:53.880960Z'
exploited: true
exploitAvailable: true
published: '2026-07-14'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T22:29:12.036Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-56155'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56155'
    label: Active Directory Federation Services Elevation of Privilege Vulnerability
tags:
  - cve.org
  - in-the-wild
  - exploit-available
  - kev
epss: 0.00346
epssPercentile: 0.25377
kev: true
kevDateAdded: '2026-07-14'
kevDueDate: '2026-07-28'
kevRansomware: false
zeroDay: true
ingestedAt: '2026-09-08T17:06:31.928Z'
---

## Overview

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

## Affected

- `windows_10_version_1607 >= 10.0.14393.0 < 10.0.14393.9339`
- `windows_10_version_1809 >= 10.0.17763.0 < 10.0.17763.9020`
- `windows_server_2012 >= 6.2.9200.0 < 6.2.9200.26226`
- `windows_server_2012_server_core_installation >= 6.2.9200.0 < 6.2.9200.26226`
- `windows_server_2012_r2 >= 6.3.9600.0 < 6.3.9600.23291`
- `windows_server_2012_r2_server_core_installation >= 6.3.9600.0 < 6.3.9600.23291`
- `windows_server_2016 >= 10.0.14393.0 < 10.0.14393.9339`
- `windows_server_2016_server_core_installation >= 10.0.14393.0 < 10.0.14393.9339`
- `windows_server_2019 >= 10.0.17763.0 < 10.0.17763.9020`
- `windows_server_2019_server_core_installation >= 10.0.17763.0 < 10.0.17763.9020`
- `windows_server_2022 >= 10.0.20348.0 < 10.0.20348.5386`
- `windows_server_2025 >= 10.0.26100.0 < 10.0.26100.33158`
- `windows_server_2025_server_core_installation >= 10.0.26100.0 < 10.0.26100.33158`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.