8.1

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3.1

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CVE-2025-21171

CVE-2025-21171: Microsoft Security Advisory CVE-2025-21171 | .NET Remote Code Execution Vulnerability

Microsoft Security Advisory CVE-2025-21171 | .NET Remote Code Execution Vulnerability

<a name="executive-summary"></a>Executive summary

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

An attacker could exploit this vulnerability by sending a specially crafted request to the vulnerable web server.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/runtime/issues/111423

<a name="mitigation-factors"></a>Mitigation factors

Microsoft has not identified any mitigating factors for this vulnerability.

<a name="affected-software"></a>Affected software

Any .NET 9.0 application running on .NET 9.0.0 or earlier.

<a name="affected-packages"></a>Affected Packages

The vulnerability affects any Microsoft .NET project if it uses any of affected packages versions listed below

<a name=".NET 9"></a>.NET 9

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.NetCore.App.Runtime.linux-arm | >= 9.0.0, < 9.0.1 | 9.0.1 Microsoft.NetCore.App.Runtime.linux-arm64 | >= 9.0.0, < 9.0.1 | 9.0.1 Microsoft.NetCore.App.Runtime.linux-musl-arm | >= 9.0.0, < 9.0.1 | 9.0.1 Microsoft.NetCore.App.Runtime.linux-musl-arm64 | >= 9.0.0, < 9.0.1 | 9.0.1 Microsoft.NetCore.App.Runtime.linux-musl-x64 | >= 9.0.0, < 9.0.1 | 9.0.1 Microsoft.NetCore.App.Runtime.linux-x64 | >= 9.0.0, < 9.0.1 | 9.0.1 | >= 9.0.0, < 9.0.1 | 9.0.1 | >= 9.0.0, < 9.0.1 | 9.0.1 | >= 9.0.0, < 9.0.1 | 9.0.1 | >= 9.0.0, < 9.0.1 | 9.0.1 | >= 9.0.0, < 9.0.1 | 9.0.1 | >= 9.0.0, < 9.0.1 | 9.0.1

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CVE-2025-21171

CVE-2025-21171:

8.1

CVSS Score

3.1

-

CVSS Score

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
Microsoft.NetCore.App.Runtime.linux-arm	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.linux-arm64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.linux-musl-arm	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.linux-musl-arm64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.linux-musl-x64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.linux-x64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.osx-arm64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.osx-x64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.win-arm	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.win-arm64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.win-x64	nuget	>= 9.0.0, < 9.0.1	9.0.1
Microsoft.NetCore.App.Runtime.win-x86	nuget	>= 9.0.0, < 9.0.1	9.0.1

Technical Details

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WAF Protection Rules

WAF Rule

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Reasoning

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8.1

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Concerned about an active attack path?

CVE-2025-21171: Microsoft Security Advisory CVE-2025-21171 | .NET Remote Code Execution Vulnerability

Microsoft Security Advisory CVE-2025-21171 | .NET Remote Code Execution Vulnerability

<a name="executive-summary"></a>Executive summary

Announcement

<a name="mitigation-factors"></a>Mitigation factors

<a name="affected-software"></a>Affected software

<a name="affected-packages"></a>Affected Packages

<a name=".NET 9"></a>.NET 9

CVE-2025-21171:

8.1

-

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Basic Information

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Technical Details

Technical Details

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Reasoning

Technical Details

8.1

8.1

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CVE-2025-21171: Microsoft Security Advisory CVE-2025-21171 | .NET Remote Code Execution Vulnerability

Microsoft Security Advisory CVE-2025-21171 | .NET Remote Code Execution Vulnerability

<a name="executive-summary"></a>Executive summary

Announcement

<a name="mitigation-factors"></a>Mitigation factors

<a name="affected-software"></a>Affected software

<a name="affected-packages"></a>Affected Packages

<a name=".NET 9"></a>.NET 9

Advisory FAQ

<a name="how-affected"></a>How do I know if I am affected?

<a name="how-fix"></a>How do I fix the issue?

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