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Advisory severityHigh7.5Microsoft Server

High [CVE-2026-84008] .NET Denial of Service Vulnerability

This high-severity Microsoft Server advisory covers CVE-2026-84008 affecting Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2019, Microsoft .NET Framework 3.5 on Windows Server 2012 R2, Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-84008 Source published

VulniPulse record published

CVE-2026-84008
Affected products & platforms
Microsoft ServerWindows Server
Open source advisory

Summary

.NET Denial of Service Vulnerability

Affected products named by the advisory: Microsoft.NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2019; Microsoft.NET Framework 3.5 on Windows Server 2012; Microsoft.NET Framework 3.5 on Windows Server 2012 R2; Microsoft.NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016; and 4 more.

Affected products named by the advisory: Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019; Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022; Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2.

Is CVE-2026-84008 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-84008 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-84008?

Upgrade to a fixed release named by Microsoft:

  • KB5127666 (build 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0)
  • KB5127696 (build 2.0.50727.9188 AND 3.0.30729.9171)
  • KB5127660 (build 2.0.50727.8987 AND 3.0.30729.8982)
  • KB5127664 (build 2.0.50727.8987 AND 3.0.30729.8982)
  • KB5126868 (build 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0)
  • KB5127685 (build 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0)
  • KB5127683 (build 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0)
  • KB5127687 (build 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0)

Confirm against the vendor advisory before you patch.

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 24 days ago·verify at source

Fixed versions
  • KB5127666 (build 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0)
  • KB5127696 (build 2.0.50727.9188 AND 3.0.30729.9171)
  • KB5127660 (build 2.0.50727.8987 AND 3.0.30729.8982)
  • KB5127664 (build 2.0.50727.8987 AND 3.0.30729.8982)
  • KB5126868 (build 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0)
  • KB5127685 (build 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0)
  • KB5127683 (build 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0)
  • KB5127687 (build 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.4811.0)

Official advisory · high-confidence parse· fetched 24 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Install the applicable security update for your platform: KB5127666, KB5127696, KB5127660, KB5127664, KB5126868, KB5127685 (see the Microsoft Update Catalog).

Official advisory · high-confidence parse· fetched 24 days ago·verify at source

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