Detections
Analytics

Security Update for Microsoft .NET Core (June 2026)

high Nessus Plugin ID 320854

Synopsis

The remote Windows host is affected by a .NET Core vulnerability

Description

The version of tested product installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the vendor advisory.

 - Improper authorization in .NET allows an authorized attacker to elevate privileges locally.
 (CVE-2026-45490)

 - Improper link resolution before file access ('link following') in .NET allows an unauthorized attacker to perform tampering locally. (CVE-2026-45491)

 - Uncontrolled resource consumption in ASP.NET Core allows an unauthorized attacker to deny service over a network. (CVE-2026-45591)

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

Solution

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

See Also

https://github.com/dotnet/announcements/issues/403

https://github.com/dotnet/announcements/issues/404

https://github.com/dotnet/announcements/issues/405

https://dotnet.microsoft.com/download/dotnet/8.0

http://www.nessus.org/u?81e45d22

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

http://www.nessus.org/u?d9285340

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

http://www.nessus.org/u?9e8206b1

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45490

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45491

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45591

https://support.microsoft.com/help/5097149

https://support.microsoft.com/help/5097150

https://support.microsoft.com/help/5097148

Plugin Details

Severity: High

ID: 320854

File Name: smb_nt_ms26_jun_dotnet_core.nasl

Version: 1.1

Type: Local

Agent: windows

Family: Windows

Published: 6/12/2026

Updated: 6/12/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: High

Base Score: 8.5

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

CVSS Score Source: CVE-2026-45490

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: installed_sw/.NET Core Windows

Patch Publication Date: 6/9/2026

Vulnerability Publication Date: 6/9/2026

Reference Information

CVE: CVE-2026-45490, CVE-2026-45491, CVE-2026-45591

IAVA: 2026-A-0565