---
id: CVE-2026-50647
title: Active Directory Federation Server Denial of Service Vulnerability
summary: >-
  Loop with unreachable exit condition ('infinite loop') in Active Directory
  Federation Services (AD FS) allows an unauthorized attacker to deny service
  over a network.
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C'
cvssSource: cna
cwe:
  - CWE-835
vendor: Microsoft
product: Microsoft .NET Framework 3.5 AND 4.7.2
affected:
  - >-
    .net_framework_3.5_and_4.7.2 >= 4.7.0 < 2.0.50727.9069 & 3.0.30729.9067 &
    4.7.4143.0
  - >-
    .net_framework_3.5_and_4.8 >= 4.8.0 < 2.0.50727.9069 & 3.0.30729.9067 &
    4.8.4803.0
  - >-
    .net_framework_3.5_and_4.8.1 >= 4.8.1 < 2.0.50727.9182 & 3.0.30729.9168 &
    4.8.9339.0
  - .net_framework_4.6.2_4.7_4.7.1_4.7.2 >= 4.7.0 < 4.7.4143.0
  - .net_framework_4.8 >= 4.8.0 < 4.8.4803.0
  - .net_framework_4.8.1 >= 4.8.0.0 < 4.8.9340.0
  - 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_10_version_21h2 >= 10.0.19044.0 < 10.0.19044.7548
  - windows_10_version_22h2 >= 10.0.19045.0 < 10.0.19045.7548
  - windows_11_version_24h2 >= 10.0.26100.0 < 10.0.26100.8875
  - windows_11_version_25h2 >= 10.0.26200.0 < 10.0.26200.8875
  - windows_11_version_26h1 >= 10.0.28000.0 < 10.0.28000.2525
  - 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: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-07-14T20:35:05.015074Z'
published: '2026-07-14'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T18:23:21.004Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-50647'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50647'
    label: Active Directory Federation Server Denial of Service Vulnerability
tags:
  - cve.org
epss: 0.01174
epssPercentile: 0.66253
ingestedAt: '2026-09-08T17:06:31.913Z'
---

## Overview

Loop with unreachable exit condition ('infinite loop') in Active Directory Federation Services (AD FS) allows an unauthorized attacker to deny service over a network.

## Affected

- `.net_framework_3.5_and_4.7.2 >= 4.7.0 < 2.0.50727.9069 & 3.0.30729.9067 & 4.7.4143.0`
- `.net_framework_3.5_and_4.8 >= 4.8.0 < 2.0.50727.9069 & 3.0.30729.9067 & 4.8.4803.0`
- `.net_framework_3.5_and_4.8.1 >= 4.8.1 < 2.0.50727.9182 & 3.0.30729.9168 & 4.8.9339.0`
- `.net_framework_4.6.2_4.7_4.7.1_4.7.2 >= 4.7.0 < 4.7.4143.0`
- `.net_framework_4.8 >= 4.8.0 < 4.8.4803.0`
- `.net_framework_4.8.1 >= 4.8.0.0 < 4.8.9340.0`
- `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_10_version_21h2 >= 10.0.19044.0 < 10.0.19044.7548`
- `windows_10_version_22h2 >= 10.0.19045.0 < 10.0.19045.7548`
- `windows_11_version_24h2 >= 10.0.26100.0 < 10.0.26100.8875`
- `windows_11_version_25h2 >= 10.0.26200.0 < 10.0.26200.8875`
- `windows_11_version_26h1 >= 10.0.28000.0 < 10.0.28000.2525`
- `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.