🛡️ CVE-2026-32178 — .net
Description
Microsoft Security Advisory CVE-2026-32178 – .NET Spoofing Vulnerability
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) | >= 8.0.0, <= 8.0.25 | 8.0.26
<a name=".NET 9"></a>.NET 9
Package name | Affected version | Patched version
------------ | ---------------- | -------------------------
[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.14 | 9.0.15
[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.14 | 9.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: Low — the attack works reliably, with no preparation.
- Privileges required: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: High — total loss, or loss the attacker controls.
- Integrity impact: None.
- Availability impact: None.
Weakness class
CVE-2026-32178 is classified as CWE-138: Improper Neutralization of Special Elements. The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as control elements or syntactic markers when they are sent to a downstream component.
Affected software
CVE-2026-32178 is recorded against 16 packages.
- .net (from 9.0.0 up to 9.0.15)
- dotnet
- dotnet-sdk
- microsoft.netcore.app.runtime.linux-arm (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.linux-arm64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.linux-musl-arm (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.linux-musl-arm64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.linux-musl-x64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.linux-x64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.osx-arm64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.osx-x64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.win-arm (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.win-arm64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.win-x64 (from 8.0.0 up to 8.0.26)
- microsoft.netcore.app.runtime.win-x86 (from 8.0.0 up to 8.0.26)
- visual-studio-2022 (from 17.14.0 up to 17.14.30)
Timeline and source
Published on 14 April 2026 and last revised on 15 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
References
msrc.microsoft.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
bugzilla.redhat.com
security.access.redhat.com
Other advisories for this package
.net has other advisories on record. If you are patching this one, these are worth checking on the same host:
- CVE-2026-70354 (7.8 High, published 11 Aug 2026)
- CVE-2026-62897 (7.0 High, published 11 Aug 2026)
- CVE-2026-62909 (7.8 High, published 11 Aug 2026)
- CVE-2026-62886 (7.8 High, published 11 Aug 2026)
- CVE-2026-62902 (6.5 Medium, published 11 Aug 2026)
- CVE-2026-62871 (7.8 High, published 11 Aug 2026)
- CVE-2026-62901 (7.5 High, published 11 Aug 2026)
- CVE-2026-62899 (5.9 Medium, published 11 Aug 2026)
Same weakness in other software
These advisories are the same class of weakness (CWE-138: Improper Neutralization of Special Elements) in other software:
- CVE-2026-26129 (7.5 High, published 7 May 2026)
- CVE-2026-20009 (5.3 Medium, published 4 Mar 2026)
- CVE-2025-48939 (4.2 Medium, published 3 Jul 2025)
- CVE-2024-51500 (5.3 Medium, published 4 Nov 2024)
- CVE-2024-38133 (7.8 High, published 13 Aug 2024)
- CVE-2023-42117 (9.8 Critical, published 3 May 2024)
- CVE-2023-22288 (4.1 Medium, published 20 Mar 2023)
- CVE-2022-2429 (6.5 Medium, published 6 Sep 2022)
CVE-2026-32178 on other distributions
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| .net | 9.0.0 | 9.0.15 |
| dotnet | — | — |
| dotnet-sdk | — | — |
| microsoft.netcore.app.runtime.linux-arm | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.linux-arm64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.linux-musl-arm | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.linux-musl-arm64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.linux-musl-x64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.linux-x64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.osx-arm64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.osx-x64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.win-arm | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.win-arm64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.win-x64 | 8.0.0 | 8.0.26 |
| microsoft.netcore.app.runtime.win-x86 | 8.0.0 | 8.0.26 |
| visual-studio-2022 | 17.14.0 | 17.14.30 |
References
Similar Threats
- High CVE-2023-33127
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- High CVE-2023-29331
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