Security Update for Microsoft .NET Core SDK (March 2026)

high Nessus Plugin ID 302121

Synopsis

The remote Windows host is affected by multiple vulnerabilities.

Description

The version of .NET Core SDK installed on the remote host is 8.x prior to 8.0.125, 8.0.4xx prior to 8.0.419, 9.x prior to 9.0.115, 9.0.3xx prior to 9.312, or 10.x prior to 10.0.104. It is, therefore, affected by multiple vulnerabilities as referenced in the vendor advisory:

- Out-of-bounds read in .NET allows an unauthorized attacker to deny service over a network. (CVE-2026-26127)

- Allocation of resources without limits or throttling in ASP.NET Core allows an unauthorized attacker to deny service over a network. (CVE-2026-26130)

- Incorrect default permissions in .NET allows an authorized attacker to elevate privileges locally.
(CVE-2026-26131)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version nuber.

Solution

Update .NET Core SDK, remove vulnerable packages and refer to the vendor advisory.

See Also

https://github.com/dotnet/announcements/issues/387

http://www.nessus.org/u?50d93f68

https://dotnet.microsoft.com/en-us/download/dotnet/8.0

https://support.microsoft.com/help/5081277

http://www.nessus.org/u?ca1d04c2

https://dotnet.microsoft.com/download/dotnet/9.0

https://support.microsoft.com/help/5081278

http://www.nessus.org/u?0a4201d8

https://dotnet.microsoft.com/download/dotnet/10.0

https://support.microsoft.com/help/5081276

Plugin Details

Severity: High

ID: 302121

File Name: smb_nt_ms26_mar_dotnet_core_sdk.nasl

Version: 1.2

Type: local

Agent: windows

Family: Windows

Published: 3/13/2026

Updated: 3/13/2026

Configuration: Enable paranoid mode

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 7.2

Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-26131

CVSS v3

Risk Factor: High

Base Score: 7.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vulnerability Information

CPE: cpe:/a:microsoft:.net_core

Required KB Items: Settings/ParanoidReport, installed_sw/.NET Core SDK Windows

Patch Publication Date: 3/10/2026

Vulnerability Publication Date: 3/10/2026

Reference Information

CVE: CVE-2026-26127, CVE-2026-26130, CVE-2026-26131

IAVA: 2026-A-0224

MSFT: MS26-5081276, MS26-5081277, MS26-5081278

MSKB: 5081276, 5081277, 5081278