CVE-2026-114159 — Microsoft.NETCore.App.Run…

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET. This advisory provides guidance on updating affected applications and components.

An oversized Portable PDB document name can be truncated during allocation and cause a heap out-of-bounds write.

CVSS Details

• Version: 3.1
• Severity: High
• Score: 8.8 (base score)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
• Weakness: CWE-122

Affected Platforms

• Platforms: Windows
• Architectures: x86, x64, Arm64

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

Microsoft.DiaSymReader.Native components bundled with the affected .NET versions listed below are affected when initializing the native reader with a Portable PDB containing an oversized document name. The Windows runtime's native stack-trace reader can reach this initialization through its native-reader fallback.

.NET on Windows

Windows runtime packages for self-contained applications

The following packages deliver the affected .NET native reader. Exposure requires the PDB-reading operation described above; the presence of the reader does not make every application or symbol-reading path vulnerable.

Windows SDK updates

The following SDK updates include the corrected .NET runtime. Update each installed Windows SDK feature band:

Advisory FAQ

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

Applications using Microsoft.DiaSymReader.Native components bundled with the affected .NET versions listed above to initialize the native reader with a Portable PDB containing an oversized document name are exposed on Windows x86, x64, and Arm64. The Windows runtime's native stack-trace reader can reach this initialization when PE metadata selects its native-reader fallback. See affected packages for the affected .NET products on Windows.

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

Update affected .NET installations and each installed SDK feature band to the versions listed above or later. If an SDK was installed through Visual Studio, update Visual Studio as well.

For applications that deploy their own .NET runtime, including self-contained applications, update the runtime used to build the application, rebuild, and redeploy. Updating a machine-wide runtime does not replace an application's embedded runtime. Restart processes that have loaded the affected native reader.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/521

Other Information

Reporting Security Issues

If you have found a potential security issue in a supported version of .NET, please report it to the Microsoft Security Response Center (MSRC) via the MSRC Researcher Portal. Further information can be found in the MSRC Report an Issue FAQ.

Security reports made through MSRC may qualify for the Microsoft .NET 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/runtime. 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.

External Links

CVE-2026-114159

Acknowledgements

• h4urek with secsys lab

Revisions

V1.0 (November 10, 2026): Advisory published.