High7.5Microsoft Server

High [CVE-2026-50355] Windows Active Directory Federation Services Denial of Service Vulnerability

This high-severity Microsoft Server advisory covers CVE-2026-50355 affecting Microsoft .NET Framework 4.8 on Windows Server 2016, Microsoft .NET Framework 4.8 on Windows Server 2012 R2, Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019.

CVE-2026-50355 Published Jul 14, 2026

CVE-2026-50355

Affected products & platforms

Microsoft ServerWindows Server

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Summary

Windows Active Directory Federation Services Denial of Service Vulnerability

Affected products named by the advisory: Microsoft.NET Framework 4.8 on Windows Server 2016; Microsoft.NET Framework 4.8 on Windows Server 2012; Microsoft.NET Framework 4.8 on Windows Server 2012 R2; Microsoft.NET Framework 3.5 AND 4.8 on Windows Server 2019; and 4 more.

Affected products named by the advisory: Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022; Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2019; Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2016; Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.

Official advisory · high-confidence parse· fetched 1 month ago·verify at source

Fixed versions

KB5101007 (build 4.8.4803.0)
KB5101009 (build 4.8.4803.0)
KB5101011 (build 4.8.4803.0)
KB5101008 (build 2.0.50727.9069 & 3.0.30729.9067 & 4.8.4803.0)
KB5101010 (build 2.0.50727.9182 & 3.0.30729.9168 & 4.8.4803.0)
KB5101006 (build 2.0.50727.9182 & 3.0.30729.9168 & 4.8.4803.0)
KB5100989 (build 2.0.50727.9069 & 3.0.30729.9067 & 4.7.4143.0)
KB5099535 (build 10.0.14393.9339)

Official advisory · high-confidence parse· fetched 1 month ago·verify at source

Mitigation checklist

Recommended fix / mitigation

Install the applicable security update for your platform: KB5101007, KB5101009, KB5101011, KB5101008, KB5101010, KB5101006 (see the Microsoft Update Catalog).

Official advisory · high-confidence parse· fetched 1 month ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Microsoft Security Update Guide (MSRC)official
Official vendor source used to discover this advisory; it remains the authority for affected products and remediation. Discovered from the machine-readable feed https://api.msrc.microsoft.com/cvrf/v3.0/updates; this link opens the Microsoft Server advisory index instead of the raw feed document.
Microsoft Server
Official vendor advisoryofficial
Official advisory page fetched and parsed for the summary, affected/fixed versions and remediation guidance it provides.
Microsoft Server
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program

Cross-references

Validate CVE metadata against the authoritative registries.

CVE-2026-50355NVD CVE.org MITRE

Official resources

Microsoft Update Catalog: KB5101007
Official documentation
Direct download of the KB5101007 security update named in the MSRC remediation data for this CVE.
Microsoft Update Catalog: KB5101009
Official documentation
Direct download of the KB5101009 security update named in the MSRC remediation data for this CVE.
Microsoft Update Catalog: KB5101011
Official documentation
Direct download of the KB5101011 security update named in the MSRC remediation data for this CVE.
MSRC Security Update Guide
Official documentation
Filter by this CVE for per-product KB numbers, severity and exploitability assessment.

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