GitHub Security Advisory: GHSA-vmwf-m9c5-3jvc
Package: Microsoft.NetCore.App.Runtime.win-x64 (NUGET)
Severity: LOW (CVSS 0.0)
CWE: CWE-138: Improper Neutralization of Special Elements
Vulnerable versions: >= 8.0.0, <= 8.0.25
Patched in: 8.0.26

Summary: Microsoft Security Advisory CVE-2026-32178 – .NET Spoofing Vulnerability 

Details:
## Executive Summary: 

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 8.0, .NET 9.0, and .NET 10.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

A vulnerability exists in System.Net.Mail where specially crafted data allows an unauthorized attacker to perform a spoofing attack over the network.

## Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/12345

## CVSS Details

- **Version:** 3.1
- **Severity:** High
- **Score:** 7.5
- **Vector:** 7.5: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
- **Weakness:** CWE-138: Improper Neutralization of Special Elements

## Affected Platforms

- **Platforms:** All
- **Architectures:** All

## <a name="affected-packages"></a>Affected Packages
The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below


### <a name=".NET 8"></a>.NET 8
Package name | Affected version | Patched version
------------ | ---------------- | -------------------------
[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm)               | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64)           | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm)     | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64)     | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64)               | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64)               | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64)                   | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm)                   | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64)               | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64)                   | >= 8.0.0, <= 8.0.25 | 8.0.26
[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86)