Improper handling of exceptional conditions in Microsoft .NET Framework and Microsoft Windows - CVE-2026-23666

Vulnerability identifier: #VU126152

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-23666

CWE-ID: CWE-755

Exploitation vector: Remote access

Exploit availability: Public exploit is available

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper handling of errors in .NET Framework. A remote attacker can send specially crafted input and perform a denial of service (DoS) attack.

Microsoft .NET Framework
Microsoft Windows

Install updates from vendor's website.

Microsoft .NET Framework - addressed in versions 2.0.50727.8982 & 3.0.30729.8976, 2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0, 2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0, 2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0, 2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0, 4.7.4141.0, 4.8.4801.0
Microsoft Windows - update to 11 26H1 10.0.28000.1836

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-23666

• Multiple vulnerabilities in Microsoft .NET Framework