CVE-2026-23666
.NET Framework Denial of Service Vulnerability
CVE-2026-23666 is fixed in 49 products on 1 platform, first by KB5082413, released April 14, 2026. It is not reported as exploited. Patch Radar priority: Urgent.
Urgent
CVSS
7.5
Critical
Exploitation
None reported
Exploitation Less Likely
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0133
71st percentile
<p>Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.</p>
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Microsoft | |||
| Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for 32-bit Systems | KB5082413 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for ARM64-based Systems | KB5082413 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for x64-based Systems | KB5082413 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for 32-bit Systems | KB5082414 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for ARM64-based Systems | KB5082414 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for x64-based Systems | KB5082414 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for 32-bit Systems | KB5082426 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for ARM64-based Systems | KB5082426 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for x64-based Systems | KB5082426 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for 32-bit Systems | KB5082426 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for ARM64-based Systems | KB5082426 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for x64-based Systems | KB5082426 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022 | KB5082427 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022 (Server Core installation) | KB5082427 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for 32-bit Systems | KB5082419 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for ARM64-based Systems | KB5082419 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for x64-based Systems | KB5082419 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for 32-bit Systems | KB5082419 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for ARM64-based Systems | KB5082419 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for x64-based Systems | KB5082419 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 22H2 for ARM64-based Systems | KB5082424 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 22H2 for x64-based Systems | KB5082424 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 23H2 for ARM64-based Systems | KB5082424 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 23H2 for x64-based Systems | KB5082424 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 24H2 for ARM64-based Systems | KB5082420 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 24H2 for x64-based Systems | KB5082420 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 25H2 for ARM64-based Systems | KB5082417 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 25H2 for x64-based Systems | KB5082417 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 26H1 for ARM64-based Systems | KB5082421 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 26H1 for x64-based Systems | KB5082421 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022 | KB5082425 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022 (Server Core installation) | KB5082425 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022, 23H2 Edition (Server Core installation) | KB5082418 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2025 | KB5082417 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2025 (Server Core installation) | KB5082417 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 on Windows Server 2012 | KB5082398 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 on Windows Server 2012 (Server Core installation) | KB5082398 | Apr 14, 2026 | |
| Microsoft .NET Framework 3.5 on Windows Server 2012 R2 | KB5082406 | Apr 15, 2026 | |
| Microsoft .NET Framework 3.5 on Windows Server 2012 R2 (Server Core installation) | KB5082406 | Apr 15, 2026 | |
| Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 | KB5082400 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 (Server Core installation) | KB5082400 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2 | KB5082402 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2 (Server Core installation) | KB5082402 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for 32-bit Systems | KB5082411 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for x64-based Systems | KB5082411 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.8 on Windows Server 2012 | KB5082403 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.8 on Windows Server 2012 (Server Core installation) | KB5082403 | Apr 14, 2026 | |
| Microsoft .NET Framework 4.8 on Windows Server 2012 R2 | KB5082404 | Apr 15, 2026 | |
| Microsoft .NET Framework 4.8 on Windows Server 2012 R2 (Server Core installation) | KB5082404 | Apr 15, 2026 | |
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