CVE-2026-23666CriticalMicrosoft CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C

Microsoft security update for CVE-2026-23666 — Microsoft .NET Framework

Published
June 2, 2026
Last Modified
—

🔗 CVE IDs covered (1)

CVE-2026-23666 →

📋 Microsoft's advisory

EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-23666. This page also shows what EchelonGraph holds for CVE-2026-23666, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.

🎯 Affected products49

  • Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for 32-bit Systems
  • Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for 32-bit Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for 32-bit Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for 32-bit Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022
  • Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022 (Server Core installation)
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for 32-bit Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for 32-bit Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 22H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 22H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 23H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 23H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 24H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 24H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 25H2 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 25H2 for x64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 26H1 for ARM64-based Systems
  • Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 26H1 for x64-based Systems
  • +19 more not shown

✅ Updates Microsoft lists: 18 KB articles

18 rows: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.

KB articleUpdateFixed build
KB5082411Security Update4.8.4801.0
KB5082403Security Update4.8.4801.0
KB5082404Security Update4.8.4801.0
KB5082414Security Update2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0
KB5082427Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0
KB5082426Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0
KB5082413Security Update2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0
KB5082400Security Update4.8.4801.0
KB5082402Security Update4.7.4141.0
KB5082425Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
KB5082419Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
KB5082424Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
KB5082417Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
KB5082418Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
KB5082420Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
KB5082398Security Update2.0.50727.8982 & 3.0.30729.8976
KB5082406Security Update2.0.50727.8982 & 3.0.30729.8976
KB5082421Security Update2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0

🧭 EchelonGraph on CVE-2026-23666

EchelonGraph score
7.5 HIGH
CISA KEV
Not listed
Fix status
A fix is available — apply it.

Description from the CVE record (CVE.org), as published by its numbering authority

Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.

Published by Microsoft Corporation, the CVE Numbering Authority that assigned CVE-2026-23666, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).

🔗 References (37)