CVE-2026-118745 — 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.

Crafted PDB line metadata can exceed the caller-provided buffer 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

On Windows x86, x64, and Arm64, Microsoft.DiaSymReader.Native versions earlier than 18.9.1-beta1.26515.1 are affected when reading crafted native PDBs.

.NET on Windows

Windows self-contained runtime packs

These runtime packs deliver the .NET runtime for Windows self-contained applications.

Windows SDK distributions

These Windows SDK distributions are affected through their bundled .NET runtime.

Windows SDK updates

Update each installed SDK feature band to the following version or later:

• .NET SDK 8.0.1xx: 8.0.134
• .NET SDK 8.0.4xx: 8.0.428
• .NET SDK 9.0.1xx: 9.0.124
• .NET SDK 9.0.3xx: 9.0.321
• .NET SDK 10.0.1xx: 10.0.115
• .NET SDK 10.0.4xx: 10.0.404
• .NET SDK 11.0.1xx: 11.0.100

Advisory FAQ

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

Applications using Microsoft.DiaSymReader.Native versions earlier than 18.9.1-beta1.26515.1 on Windows x86, x64, and Arm64 to read crafted native PDBs are exposed. 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.

Microsoft.DiaSymReader.Native is delivered through .NET Core rather than as a standalone customer NuGet update. For applications that deploy their own affected .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.

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.

Announcement

https://github.com/dotnet/announcements/issues/524

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-2026-118745

Acknowledgements

• Quac Tran

Revisions

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