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.NET NuGet

CVE-2025-26646

HIGH

CVE-2025-26646 is a high-severity (CVSS 8) CWE-73 vulnerability in Microsoft.Build.Tasks.Core. O3 Security confirms whether CVE-2025-26646 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Microsoft.Build.Tasks.Core .NET Spoofing Vulnerability

Also known asBIT-dotnet-2025-26646BIT-dotnet-sdk-2025-26646GHSA-h4j7-5rxr-p4wc
Published
May 13, 2025
Updated
Apr 10, 2026
Affected
7 pkgs
Patched
7 / 7
Exploits
None indexed

Real-World Exposure

7 pkgs affected
.NETMicrosoft.Build.Tasks.Core.NETMicrosoft.Build.Tasks.Core.NETMicrosoft.Build.Tasks.Core.NETMicrosoft.Build.Tasks.Core.NETMicrosoft.Build.Tasks.Core.NETMicrosoft.Build.Tasks.Core.NETMicrosoft.Build.Tasks.Core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

External control of file name or path in .NET, Visual Studio, and Build Tools for Visual Studio allows an authorized attacker to perform spoofing over a network.

Affected Packages

7 total 7 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetMicrosoft.Build.Tasks.Core15.8.166&&< 15.9.3015.9.30
.NETNuGetMicrosoft.Build.Tasks.Core16.0.461&&< 16.11.616.11.6
.NETNuGetMicrosoft.Build.Tasks.Core17.0.0&&< 17.8.2917.8.29
.NETNuGetMicrosoft.Build.Tasks.Core17.9.5&&< 17.10.2917.10.29
.NETNuGetMicrosoft.Build.Tasks.Core17.11.4&&< 17.12.3617.12.36
.NETNuGetMicrosoft.Build.Tasks.Core17.12.6&&< 17.13.2617.13.26

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.Build.Tasks.Core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update Microsoft.Build.Tasks.Core to 15.9.30 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-26646 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2025-26646 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2025-26646. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

External control of file name or path in .NET, Visual Studio, and Build Tools for Visual Studio allows an authorized attacker to perform spoofing over a network.
O3 Security · Impact-Aware SCA

Is CVE-2025-26646 in your dependencies?

O3 detects CVE-2025-26646 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.