High

.NET Framework Denial of Service Vulnerability

Type: advisorySource: Official CVE List1 source record

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

Announced 14 Apr 2026Group revision 1

CVE-2026-23666

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-23666

Microsoft .NET Framework 3.5

Source reference: /containers/cna/affected/0/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Microsoft .NET Framework 3.5 AND 4.7.2

Source reference: /containers/cna/affected/1/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Microsoft .NET Framework 3.5 AND 4.8

Source reference: /containers/cna/affected/2/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Microsoft .NET Framework 3.5 AND 4.8.1

Source reference: /containers/cna/affected/3/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2

Source reference: /containers/cna/affected/4/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Microsoft .NET Framework 4.8

Source reference: /containers/cna/affected/5/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "Microsoft",
    "product": "Microsoft .NET Framework 3.5",
    "versions": [
      {
        "status": "affected",
        "version": "3.5.0",
        "lessThan": "2.0.50727.8982 & 3.0.30729.8976",
        "versionType": "custom"
      }
    ],
    "platforms": [
      "Windows Server 2012",
      "Windows Server 2012 (Server Core installation)",
      "Windows Server 2012 R2",
      "Windows Server 2012 R2 (Server Core installation)"
    ]
  },
  {
    "vendor": "Microsoft",
    "product": "Microsoft .NET Framework 3.5 AND 4.7.2",
    "versions": [
      {
        "status": "affected",
        "version": "4.7.0",
        "lessThan": "2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0",
        "versionType": "custom"
      }
    ],
    "platforms": [
      "Windows 10 Version 1809 for 32-bit Systems",
      "Windows 10 Version 1809 for ARM64-based Systems",
      "Windows 10 Version 1809 for x64-based Systems"
    ]
  },
  {
    "vendor": "Microsoft",
    "product": "Microsoft .NET Framework 3.5 AND 4.8",
    "versions": [
      {
        "status": "affected",
        "version": "4.8.0",
        "lessThan": "2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0",
        "versionType": "custom"
      }
    ],
    "platforms": [
      "Windows 10 Version 1809 for 32-bit Systems",
      "Windows 10 Version 1809 for ARM64-based Systems",
      "Windows 10 Version 1809 for x64-based Systems",
      "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 32-bit Systems",
      "Windows 10 Version 22H2 for ARM64-based Systems",
      "Windows 10 Version 22H2 for x64-based Systems",
      "Windows Server 2022",
      "Windows Server 2022 (Server Core installation)"
    ]
  },
  {
    "vendor": "Microsoft",
    "product": "Microsoft .NET Framework 3.5 AND 4.8.1",
    "versions": [
      {
        "status": "affected",
        "version": "4.8.1",
        "lessThan": "2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0",
        "versionType": "custom"
      }
    ],
    "platforms": [
      "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 32-bit Systems",
      "Windows 10 Version 22H2 for ARM64-based Systems",
      "Windows 10 Version 22H2 for x64-based Systems",
      "Windows 11 Version 22H2 for ARM64-based Systems",
      "Windows 11 Version 22H2 for x64-based Systems",
      "Windows 11 Version 23H2 for ARM64-based Systems",
      "Windows 11 Version 23H2 for x64-based Systems",
      "Windows 11 Version 24H2 for ARM64-based Systems",
      "Windows 11 Version 24H2 for x64-based Systems",
      "Windows 11 Version 25H2 for ARM64-based Systems",
      "Windows 11 Version 25H2 for x64-based Systems",
      "Windows 11 Version 26H1 for ARM64-based Systems",
      "Windows 11 version 26H1 for x64-based Systems",
      "Windows Server 2022",
      "Windows Server 2022 (Server Core installation)",
      "Windows Server 2022, 23H2 Edition (Server Core installation)",
      "Windows Server 2025",
      "Windows Server 2025 (Server Core installation)"
    ]
  },
  {
    "vendor": "Microsoft",
    "product": "Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2",
    "versions": [
      {
        "status": "affected",
        "version": "4.7.0",
        "lessThan": "4.8.4801.0",
        "versionType": "custom"
      }
    ],
    "platforms": [
      "Windows Server 2012",
      "Windows Server 2012 (Server Core installation)",
      "Windows Server 2012 R2",
      "Windows Server 2012 R2 (Server Core installation)"
    ]
  },
  {
    "vendor": "Microsoft",
    "product": "Microsoft .NET Framework 4.8",
    "versions": [
      {
        "status": "affected",
        "version": "4.8.0",
        "lessThan": "4.8.4801.0",
        "versionType": "custom"
      }
    ],
    "platforms": [
      "Windows 10 Version 1607 for 32-bit Systems",
      "Windows 10 Version 1607 for x64-based Systems",
      "Windows Server 2012",
      "Windows Server 2012 (Server Core installation)",
      "Windows Server 2012 R2",
      "Windows Server 2012 R2 (Server Core installation)"
    ]
  }
]

Related CVEs: CVE-2026-23666
Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event: #29059 · Revision 1
Added to Heist Feed: Sun, 25 Oct 2026 07:52:13 GMT
Publisher date: Tue, 14 Apr 2026 16:57:53 GMT

Read the original announcement

Revision history

25 Oct 2026CVE-2026-23666 · Revision 1Source updated