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Vulnerability details: VCID-4zux-cmaa-w3gd
Vulnerability ID VCID-4zux-cmaa-w3gd
Aliases CVE-2025-26646
GHSA-h4j7-5rxr-p4wc
Summary Microsoft.Build.Tasks.Core .NET Spoofing Vulnerability # 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.Tasks.Core) |>= 15.8.166, <=15.9.20<br />>=16.0.461, <= 16.11.0<br />>= 17.0.0, <= 17.8.3<br/>>= 17.9.5, <= 17.10.4<br />17.11.4<br />17.12.6 <br />17.13.9 | 15.9.30<br />16.11.6<br />17.8.29<br/>17.10.29<br />17.12.36<br />17.13.26 <br />17.14.8 ## Advisory FAQ ### <a name="how-affected"></a>How do I know if I am affected? If you have a .NET SDK with a version listed, or an affected package listed in [affected software](#affected-packages) or [affected packages](#affected-software), you're exposed to the vulnerability. ### <a name="how-fix"></a>How do I fix the issue? 1. To fix the issue please install the latest version of .NET 9.0 SDK or .NET 8.0 SDK. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs. 2. If your application references the vulnerable package, update the package reference to the patched version. * You can list the versions you have installed by running the `dotnet --info` command. You will see output like the following; ``` .NET SDK: Version: 9.0.100 Commit: 59db016f11 Workload version: 9.0.100-manifests.3068a692 MSBuild version: 17.12.7+5b8665660 Runtime Environment: OS Name: Mac OS X OS Version: 15.2 OS Platform: Darwin RID: osx-arm64 Base Path: /usr/local/share/dotnet/sdk/9.0.100/ .NET workloads installed: There are no installed workloads to display. Configured to use loose manifests when installing new manifests. Host: Version: 9.0.0 Architecture: arm64 Commit: 9d5a6a9aa4 .NET SDKs installed: 9.0.100 [/usr/local/share/dotnet/sdk] .NET runtimes installed: Microsoft.AspNetCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.NETCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Other architectures found: x64 [/usr/local/share/dotnet] registered at [/etc/dotnet/install_location_x64] Environment variables: Not set global.json file: Not found Learn more: https://aka.ms/dotnet/info Download .NET: https://aka.ms/dotnet/download ``` * If you're using .NET 9.0, you should download and install the appropriate SDK: `.NET 9.0.300` for Visual Studio 2022 v17.14, `.NET 9.0.204` for v17.13, or `.NET 9.0.106` for v17.12. Download from https://dotnet.microsoft.com/download/dotnet-core/9.0. * If you're using .NET 8.0, you should download and install the appropriate SDK: `.NET 8.0.410` for Visual Studio 2022 v17.11, `.NET 8.0.313` for v17.10, or `.NET 8.0.116` for v17.8. Download from https://dotnet.microsoft.com/download/dotnet-core/8.0. Once you have installed the updated SDK, restart your apps for the update to take effect. ## Other Information ### Reporting Security Issues If you have found a potential security issue in .NET 8.0 or .NET 9.0, please email details to secure@microsoft.com. Reports may qualify for the Microsoft .NET Core & .NET 5 Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at <https://aka.ms/corebounty>. ### Support You can ask questions about this issue on GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/aspnetcore. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the linked discussion issue. ### Disclaimer The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (4)
CWE-73 External Control of File Name or Path
CWE-290 Authentication Bypass by Spoofing
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 8.0 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2025-26646.json
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
epss 0.00236 https://api.first.org/data/v1/epss?cve=CVE-2025-26646
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-h4j7-5rxr-p4wc
cvssv3.1 8.0 https://github.com/dotnet/announcements/issues/356
generic_textual HIGH https://github.com/dotnet/announcements/issues/356
cvssv3.1 8.0 https://github.com/dotnet/msbuild
generic_textual HIGH https://github.com/dotnet/msbuild
cvssv3.1 8.0 https://github.com/dotnet/msbuild/issues/11846
generic_textual HIGH https://github.com/dotnet/msbuild/issues/11846
cvssv3.1 8.0 https://github.com/dotnet/msbuild/security/advisories/GHSA-h4j7-5rxr-p4wc
cvssv3.1_qr HIGH https://github.com/dotnet/msbuild/security/advisories/GHSA-h4j7-5rxr-p4wc
generic_textual HIGH https://github.com/dotnet/msbuild/security/advisories/GHSA-h4j7-5rxr-p4wc
cvssv3.1 8 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
cvssv3.1 8.0 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
generic_textual HIGH https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
ssvc Track https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
cvssv3.1 8.0 https://nvd.nist.gov/vuln/detail/CVE-2025-26646
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2025-26646
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2025-26646.json
https://api.first.org/data/v1/epss?cve=CVE-2025-26646
https://github.com/dotnet/announcements/issues/356
https://github.com/dotnet/msbuild
https://github.com/dotnet/msbuild/issues/11846
https://github.com/dotnet/msbuild/security/advisories/GHSA-h4j7-5rxr-p4wc
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
https://nvd.nist.gov/vuln/detail/CVE-2025-26646
2365317 https://bugzilla.redhat.com/show_bug.cgi?id=2365317
GHSA-h4j7-5rxr-p4wc https://github.com/advisories/GHSA-h4j7-5rxr-p4wc
RHSA-2025:7571 https://access.redhat.com/errata/RHSA-2025:7571
RHSA-2025:7589 https://access.redhat.com/errata/RHSA-2025:7589
RHSA-2025:7598 https://access.redhat.com/errata/RHSA-2025:7598
RHSA-2025:7599 https://access.redhat.com/errata/RHSA-2025:7599
RHSA-2025:7600 https://access.redhat.com/errata/RHSA-2025:7600
RHSA-2025:7601 https://access.redhat.com/errata/RHSA-2025:7601
RHSA-2025:7603 https://access.redhat.com/errata/RHSA-2025:7603
RHSA-2026:9080 https://access.redhat.com/errata/RHSA-2026:9080
RHSA-2026:9205 https://access.redhat.com/errata/RHSA-2026:9205
USN-7509-1 https://usn.ubuntu.com/7509-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2025-26646.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://github.com/dotnet/announcements/issues/356
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://github.com/dotnet/msbuild
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://github.com/dotnet/msbuild/issues/11846
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://github.com/dotnet/msbuild/security/advisories/GHSA-h4j7-5rxr-p4wc
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C Found at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2025-05-14T15:57:11Z/ Found at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-26646
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2025-26646
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.46479
EPSS Score 0.00236
Published At April 2, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:57:01.798887+00:00 GithubOSV Importer Import https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/05/GHSA-h4j7-5rxr-p4wc/GHSA-h4j7-5rxr-p4wc.json 38.0.0