GHSA-73j8-2gch-69rq .NET Denial of Service Vulnerability

• NuGet Microsoft.Bcl.Memory: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.linux-arm: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.linux-arm64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.linux-musl-arm: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.linux-musl-arm64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.linux-musl-x64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.linux-x64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.osx-arm64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.osx-x64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.win-arm: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.win-arm64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.win-x64: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.NetCore.App.Runtime.win-x86: >= 9.0.0, < 9.0.14 → fixed in 9.0.14 • NuGet Microsoft.Bcl.Memory: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.linux-arm: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.linux-arm64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.linux-musl-arm: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.linux-musl-arm64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.linux-musl-x64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.linux-x64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.osx-arm64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.osx-x64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.win-arm: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.win-x64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.win-x86: >= 10.0.0, < 10.0.4 → fixed in 10.0.4 • NuGet Microsoft.NetCore.App.Runtime.win-arm64: >= 10.0.0, < 10.0.4 → fixed in 10.0.4

Microsoft Security Advisory CVE-2026-26127 – .NET Denial of Service Vulnerability Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 9.0 and .NET 10.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A denial of service vulnerability exists in .NET and Microsoft.Bcl.Memory due to an out-of-bounds read when decoding malformed Base64Url input. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/384 CVSS Details • Version: 3.1 • Score: 7.5 • Vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C` • Severity: High • Weakness: CWE-129 (Improper Validation of Array Index); CWE-125 (Out-of-bounds Read) Affected Platforms • Platforms: All • Architectures: All Affected Products .NET 9 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.NetCore.App.Runtime.linux-arm | >= 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, = 9.0.0, .NET 10 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.NetCore.App.Runtime.linux-arm | >= 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, = 10.0.0, Microsoft.Bcl.Memory 9.0.14 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.Bcl.Memory | >= 9.0.0, Microsoft.Bcl.Memory 10.0.4 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.Bcl.Memory | >= 10.0.0, How to fix the issue To update the Microsoft.Bcl.Memory NuGet package, apply one of the following methods: NuGet Package Manager UI in Visual Studio: • Open the project in Visual Studio. • Right-click on the project in Solution Explorer and select "Manage NuGet Packages..." or navigate to "Project > Manage NuGet Packages". • In the NuGet Package Manager window, select the "Updates" tab. This tab lists packages with available updates from the configured package sources. • Select the package(s) to update. A specific version can be chosen from the dropdown, or the latest available version can be selected. • Click the "Update" button. Using the NuGet Package Manager Console in Visual Studio: • Open the project in Visual Studio. • Navigate to "Tools > NuGet Package Manager > Package Manager Console". • To update a specific package to its latest version, run the following Update-Package command: ``` Update-Package -Id Microsoft.Bcl.Memory ``` Using the .NET CLI (Command Line Interface): • Open a terminal or command prompt in the project's directory. • To update a specific package to its latest version, run the following command: ``` dotnet package update Microsoft.Bcl.Memory ``` Once the NuGet package reference has been updated, the application must be recompiled and redeployed. Additionally, it is recommended to update the runtime and/or SDKs, but unless the application targets .NET 9 or higher, updating the runtime and/or SDK is not a required step to patch this vulnerability. Other Information Reporting Security Issues If a potential security issue has been found in a supported version of .NET, it should be reported 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 Questions about this issue can be asked on GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/runtime. The Announce…