Microsoft Security Advisory CVE-2026-69522 – .NET and Visual Studio Remote Code Execution Vulnerability

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.DiaSymReader.Native. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

An out of bounds write can occur when processing PDB files.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/439

CVSS Details

• Version: 3.1
• Severity: High
• Score: 8.8
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Weakness: CWE-122 (Heap-based Buffer Overflow)

Affected Platforms

• Platforms: Windows
• Architectures: All

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

The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below

Supported .NET Framework versions listed in the Microsoft Security Update Guide are also affected. Install the September 2026 .NET Framework security update applicable to a project's Windows version.

<a name=".NET 11 RC1"></a>.NET 11 RC1

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.DiaSymReader.Native | >= 17.10.0-beta1.24272.1, <= 18.9.0-beta1.26405.1 | 18.9.0-beta1.26405.2

<a name=".NET 10"></a>.NET 10

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.DiaSymReader.Native | >= 17.12.0-beta1.24603.5, <= 18.9.0-beta1.26405.1 | 18.9.0-beta1.26405.2

<a name=".NET 9"></a>.NET 9

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.DiaSymReader.Native | >= 17.12.0-beta1.24603.5, <= 18.9.0-beta1.26405.1 | 18.9.0-beta1.26405.2

<a name=".NET 8"></a>.NET 8

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.DiaSymReader.Native | >= 17.12.0-beta1.24603.5, <= 18.9.0-beta1.26405.1 | 18.9.0-beta1.26405.2

Advisory FAQ

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

If using a package listed in affected packages, a project is 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 or Visual Studio. .NET Framework users must install the September 2026 security update applicable to their Windows version.
2. If a developer's application references Microsoft.DiaSymReader.Native, update the package reference to version 18.9.0-beta1.26405.2 or later.

Once users have installed the updated runtime, SDK, Visual Studio, or package, they should restart their apps for the update to take effect.

Other Information

Reporting Security Issues

If users 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

Users 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. Users 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-2026-69522

Acknowledgements

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Revisions

V1.0 (09/08/2026): Advisory published.