Search threats, CVEs… ⌘K
Back to vendor advisories
Microsoft Security Response CenterCVE-2026-50647

Active Directory Federation Server Denial of Service Vulnerability

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

Read the vendor bulletin Get alerts for Windows
7.5CVSS out of 10High severity
Scope

What the vendor says is affected

  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 10 Version 1809 for x64-based Systems
  • Windows Server 2019
  • Windows Server 2019 (Server Core installation)
  • Windows Server 2022
  • Windows 10 Version 21H2 for 32-bit Systems
  • Windows 10 Version 21H2 for ARM64-based Systems
  • Windows 10 Version 21H2 for x64-based Systems
  • Windows 10 Version 22H2 for x64-based Systems
  • Windows 10 Version 22H2 for ARM64-based Systems
  • Windows 10 Version 22H2 for 32-bit Systems
  • Windows Server 2025 (Server Core installation)
  • Windows 11 Version 25H2 for ARM64-based Systems
  • Windows 11 Version 25H2 for x64-based Systems
  • Windows 11 Version 24H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for x64-based Systems
  • Windows Server 2025
  • Windows 11 version 26H1 for x64-based Systems
  • Windows 11 Version 26H1 for ARM64-based Systems
  • Windows 10 Version 1607 for 32-bit Systems
  • Windows 10 Version 1607 for x64-based Systems
  • Windows Server 2016
  • Windows Server 2016 (Server Core installation)
  • Windows Server 2012

Versions the vendor lists as fixed

  • 10.0.17763.9020
  • 10.0.20348.5386
  • 10.0.19044.7548
  • 10.0.19045.7548
  • 10.0.26100.33158
  • 10.0.26200.8875
  • 10.0.26100.8875
  • 10.0.28000.2525
  • 10.0.14393.9339
  • 6.2.9200.26226
  • 6.3.9600.23291
  • 4.8.4803.0
  • 2.0.50727.9069 & 3.0.30729.9067 & 4.8.4803.0
  • 2.0.50727.9182 & 3.0.30729.9168 & 4.8.4803.0
  • 2.0.50727.9069 & 3.0.30729.9067 & 4.7.4143.0
  • 2.0.50727.8983 & 3.0.30729.8978 & 4.7.4143.0
  • 4.7.4143.0
  • 2.0.50727.9182 & 3.0.30729.9168 & 4.8.9339.0
  • 2.0.50727.9182 & 3.0.30729.9168 & 4.8.9340.0
  • 4.8.9340.0
Next step

What the vendor recommends

Install KB5099538. Install KB5099540. Install KB5099539. Install KB5099536. Install KB5101650. Install KB5101649. Install KB5099535. Install KB5099445. Install KB5099444. Install KB5101007. Install KB5101009. Install KB5101011. Install KB5101008. Install KB5101010. Install KB5101006. Install KB5100989. Install KB5100990. Install KB5100991. Install KB5101005. Install KB5101000. Install KB5100998. Install KB5101004. Install KB5101001. Install KB5101002.

Review the complete instructions on the vendor's site
Timeline

When this advisory changed

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Updated by Microsoft Security Response Center

    The vendor changed the advisory after it was first published.

  3. Added to SecurityAlert

    We collected the advisory from the official source.

Vulnerabilities

CVEs named in this advisory

CVE-2026-50647View CVSS, KEV, EPSS, and threat context
Keep investigating
See every advisory from this vendor