Microsoft.Build.Tasks.Core .NET Spoofing Vulnerability
Date: 2025-05
Affected: nuget/Microsoft.Build.Tasks.Core, nuget/Microsoft.Build.Tasks.Core, nuget/Microsoft.Build.Tasks.Core
Attack vector: other
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2025-26646
CWE: CWE-73
CVSS: 8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H)

# Microsoft Security Advisory CVE-2025-26646: .NET Spoofing Vulnerability ## <a name="executive-summary"></a>Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 9.0.xxx and .NET 8.0.xxx SDK. This advisory also provides guidance on what developers can do to update their applications to address this vulnerability. A vulnerability exists in .NET SDK or MSBuild applications where external control of file name or path allows an unauthorized attacked to perform spoofing over a network. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/356 ### <a name="mitigation-factors"></a>Mitigation factors Projects which do not utilize the [DownloadFile](https://learn.microsoft.com/visualstudio/msbuild/downloadfile-task) build task are not susceptible to this vulnerability. ## <a name="affected-software"></a>Affected software * Any installation of .NET 9.0.105 SDK, .NET 9.0.203 SDK or earlier. * Any installation of .NET 8.0.115 SDK, .NET 8.0.311 or .NET 8.0.312 SDK, .NET 8.0.408 or .NET 8.0.409 SDK or earlier. ## <a name="affected-packages"></a>Affected Packages The vulnerability affects any Microsoft .NET Core project if it uses any of affected packages versions listed below Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [Microsoft.Build.Tasks.Core](https://www.nuget.org/packages/Microsoft.Build.Task


Mitigations:

Architectural layers (MAESTRO):