CVE-2026-50659 .NET Spoofing Vulnerability
Medium 6.5
Published
Updated
Check this codebase for CVE-2026-50659 and fix it if it is affected.
What it is: CVE-2026-50659 is a medium-severity cross-site scripting vulnerability in Microsoft .Net, published on 14 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-50659 in the wild and no public exploit code.
Affected packages and fixed versions:
- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): affected from 10.0.0; fixed in 10.0.10
- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): affected from 10.0.0; fixed in 10.0.10
- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): affected from 8.0.0; fixed in 8.0.29
- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): affected from 8.0.0; fixed in 8.0.29
- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): affected from 9.0.0; fixed in 9.0.18
- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): affected from 9.0.0; fixed in 9.0.18
- dotnet (Bitnami): affected from 8.0.0; fixed in 8.0.29, 9.0.18, 10.0.6
- dotnet-sdk (Bitnami): affected from 8.0.0; fixed in 8.0.29, 9.0.18, 10.0.6
- Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet): affected from 10.0.0; fixed in 10.0.10
- Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet): affected from 10.0.0; fixed in 10.0.10
- Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet): affected from 8.0.0; fixed in 8.0.29
- Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet): affected from 8.0.0; fixed in 8.0.29
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-50659/ (Markdown: https://insights.sbomify.com/CVE-2026-50659/index.md)
An authorized attacker can perform spoofing attacks via improper output encoding in the .NET framework, requiring a security patch.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-50659?
CVE-2026-50659 is a medium-severity cross-site scripting vulnerability in Microsoft .Net, published on 14 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Improper encoding or escaping of output in .NET allows an authorized attacker to perform spoofing over a network.
Weakness: CWE-116
Which versions are affected by CVE-2026-50659?
40 open source packages ship an affected version, including Microsoft.NetCore.App.Runtime.linux-arm, dotnet and dotnet-sdk. It affects 4 products.
| Package | Affected | Fixed in |
|---|---|---|
Microsoft.NetCore.App.Runtime.linux-arm NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-arm NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-arm NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-arm NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-arm NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-arm NuGet | From 9.0.0 | 9.0.18 |
34 more packages
dotnet Bitnami | From 8.0.0 | 8.0.29, 9.0.18, 10.0.6 |
dotnet-sdk Bitnami | From 8.0.0 | 8.0.29, 9.0.18, 10.0.6 |
Microsoft.NetCore.App.Runtime.linux-arm64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-arm64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-arm64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-arm64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-arm64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-arm64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-musl-arm NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-musl-arm NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-musl-arm NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-musl-arm NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-musl-arm NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-musl-arm NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-musl-arm64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-musl-arm64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-musl-arm64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-musl-arm64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-musl-arm64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-musl-arm64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-musl-x64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-musl-x64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-musl-x64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-musl-x64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-musl-x64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-musl-x64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-x64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-x64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.linux-x64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-x64 NuGet | From 8.0.0 | 8.0.29 |
Microsoft.NetCore.App.Runtime.linux-x64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.linux-x64 NuGet | From 9.0.0 | 9.0.18 |
Microsoft.NetCore.App.Runtime.osx-arm64 NuGet | From 10.0.0 | 10.0.10 |
Microsoft.NetCore.App.Runtime.osx-arm64 NuGet | From 10.0.0 | 10.0.10 |
Products include Microsoft .Net, Microsoft .Net Framework, Microsoft Visual Studio 2022, Microsoft Visual Studio 2026.
How do I fix CVE-2026-50659?
Upgrade Microsoft.NetCore.App.Runtime.linux-arm to a fixed version for your release line: 10.0.10, 8.0.29 or 9.0.18.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-50659 being exploited?
There is no known exploitation of CVE-2026-50659 in the wild and no public exploit code.
Other vulnerabilities in Microsoft .Net
- CVE-2024-43498 .NET and Visual Studio Remote Code Execution Vulnerability
- CVE-2024-0057 NET, .NET Framework, and Visual Studio Security Feature Bypass Vulnerability
- CVE-2026-96957 .NET Security Feature Bypass Vulnerability
- CVE-2026-69439 .NET and Visual Studio Elevation of Privilege Vulnerability
- CVE-2026-71328 .NET and Visual Studio Remote Code Execution Vulnerability
Sources
Also known as BIT-dotnet-2026-50659, BIT-dotnet-sdk-2026-50659, GHSA-74jp-vm22-8q8x, MINI-44r4-r76f-g9xf, MINI-m947-67c6-w459, UBUNTU-CVE-2026-50659.