Skip to content
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
{
"schema_version": "1.4.0",
"id": "GHSA-73j8-2gch-69rq",
"modified": "2026-03-11T21:11:44Z",
"modified": "2026-03-11T21:11:46Z",
"published": "2026-03-11T21:11:44Z",
"aliases": [
"CVE-2026-26127"
],
"summary": ".NET Denial of Service Vulnerability",
"details": "# Microsoft Security Advisory CVE-2026-26127 – .NET Denial of Service Vulnerability\n\n## Executive summary\n\nMicrosoft 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.\n\nA denial of service vulnerability exists in .NET and Microsoft.Bcl.Memory due to an out-of-bounds read when decoding malformed Base64Url input.\n\n## Announcement\n\nAnnouncement for this issue can be found at https://github.com/dotnet/announcements/issues/12345\n\n## CVSS Details\n\n- **Version:** 3.1\n- **Score:** 7.5\n- **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`\n- **Severity:** High\n- **Weakness:** CWE-129 (Improper Validation of Array Index); CWE-125 (Out-of-bounds Read)\n\n## Affected Platforms\n\n- **Platforms:** All\n- **Architectures:** All\n\n## Affected Products\n\n### <a name=\".NET 9\"></a>.NET 9\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\".NET 10\"></a>.NET 10\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"Micorsoft.Bcl.Memory 9.0.14\"></a>Micorsoft.Bcl.Memory 9.0.14\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\"Micorsoft.Bcl.Memory 10.0.4\"></a>Micorsoft.Bcl.Memory 10.0.4\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"how-fix\"></a>How do I fix the issue?\n\nTo update the Microsoft.Bcl.Memory NuGet package, use one of the following methods:\n\nNuGet Package Manager UI in Visual Studio:\n- Open your project in Visual Studio.\n- Right-click on your project in Solution Explorer and select \"Manage NuGet Packages...\" or navigate to \"Project > Manage NuGet Packages\".\n- In the NuGet Package Manager window, select the \"Updates\" tab. This tab lists packages with available updates from your configured package sources.\n- Select the package(s) you wish to update. You can choose a specific version from the dropdown or update to the latest available version.\n- Click the \"Update\" button.\n\nUsing the NuGet Package Manager Console in Visual Studio:\n- Open your project in Visual Studio.\n- Navigate to \"Tools > NuGet Package Manager > Package Manager Console\".\n- To update a specific package to its latest version, use the following Update-Package command:\n\n```Update-Package -Id Microsoft.Bcl.Memory```\n\nUsing the .NET CLI (Command Line Interface):\n- Open a terminal or command prompt in your project's directory.\n- To update a specific package to its latest version, use the following add package command:\n\n```dotnet package update Microsoft.Bcl.Memory```\n\nOnce you have updated the nuget package reference you must recompile and deploy your application. Additionally we recommend you update your runtime and/or SDKs, but unless you are targeting .NET 9 or higher, updating your runtime and/or SDK is not a required step to patch this vulnerability.\n\n## Other Information\n\n### Reporting Security Issues\n\nIf 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](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue).\n\nSecurity 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.\n\n### Support\n\nYou 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.\n\n### Disclaimer\n\nThe 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.\n\n### External Links\n\n[CVE-2026-26127](https://www.cve.org/CVERecord?id=CVE-2026-26127)\n\n### Revisions\n\nV1.0 (March 10, 2026): Advisory published.",
"details": "# Microsoft Security Advisory CVE-2026-26127 – .NET Denial of Service Vulnerability\n\n## Executive summary\n\nMicrosoft 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.\n\nA denial of service vulnerability exists in .NET and Microsoft.Bcl.Memory due to an out-of-bounds read when decoding malformed Base64Url input.\n\n## Announcement\n\nAnnouncement for this issue can be found at https://github.com/dotnet/announcements/issues/384\n\n## CVSS Details\n\n- **Version:** 3.1\n- **Score:** 7.5\n- **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`\n- **Severity:** High\n- **Weakness:** CWE-129 (Improper Validation of Array Index); CWE-125 (Out-of-bounds Read)\n\n## Affected Platforms\n\n- **Platforms:** All\n- **Architectures:** All\n\n## Affected Products\n\n### <a name=\".NET 9\"></a>.NET 9\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\".NET 10\"></a>.NET 10\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"Micorsoft.Bcl.Memory 9.0.14\"></a>Micorsoft.Bcl.Memory 9.0.14\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\"Micorsoft.Bcl.Memory 10.0.4\"></a>Micorsoft.Bcl.Memory 10.0.4\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"how-fix\"></a>How do I fix the issue?\n\nTo update the Microsoft.Bcl.Memory NuGet package, use one of the following methods:\n\nNuGet Package Manager UI in Visual Studio:\n- Open your project in Visual Studio.\n- Right-click on your project in Solution Explorer and select \"Manage NuGet Packages...\" or navigate to \"Project > Manage NuGet Packages\".\n- In the NuGet Package Manager window, select the \"Updates\" tab. This tab lists packages with available updates from your configured package sources.\n- Select the package(s) you wish to update. You can choose a specific version from the dropdown or update to the latest available version.\n- Click the \"Update\" button.\n\nUsing the NuGet Package Manager Console in Visual Studio:\n- Open your project in Visual Studio.\n- Navigate to \"Tools > NuGet Package Manager > Package Manager Console\".\n- To update a specific package to its latest version, use the following Update-Package command:\n\n```Update-Package -Id Microsoft.Bcl.Memory```\n\nUsing the .NET CLI (Command Line Interface):\n- Open a terminal or command prompt in your project's directory.\n- To update a specific package to its latest version, use the following add package command:\n\n```dotnet package update Microsoft.Bcl.Memory```\n\nOnce you have updated the nuget package reference you must recompile and deploy your application. Additionally we recommend you update your runtime and/or SDKs, but unless you are targeting .NET 9 or higher, updating your runtime and/or SDK is not a required step to patch this vulnerability.\n\n## Other Information\n\n### Reporting Security Issues\n\nIf 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](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue).\n\nSecurity 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.\n\n### Support\n\nYou 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.\n\n### Disclaimer\n\nThe 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.\n\n### External Links\n\n[CVE-2026-26127](https://www.cve.org/CVERecord?id=CVE-2026-26127)\n\n### Revisions\n\nV1.0 (March 10, 2026): Advisory published.",
Copy link

Copilot AI Mar 12, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The .NET CLI example in the details text uses dotnet package update Microsoft.Bcl.Memory, which is not a standard dotnet SDK command for updating NuGet references (elsewhere in this repo advisories use dotnet add package ...). This guidance is likely to fail for readers; please update the command to the correct dotnet CLI invocation (and ideally include the patched version).

Copilot uses AI. Check for mistakes.
Copy link

Copilot AI Mar 12, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

In the details markdown, the headings/anchors for the Bcl.Memory sections spell "Micorsoft" instead of "Microsoft" (appears in both the 9.0.14 and 10.0.4 section titles). This is user-visible and should be corrected to the proper vendor name.

Suggested change
"details": "# Microsoft Security Advisory CVE-2026-26127 – .NET Denial of Service Vulnerability\n\n## Executive summary\n\nMicrosoft 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.\n\nA denial of service vulnerability exists in .NET and Microsoft.Bcl.Memory due to an out-of-bounds read when decoding malformed Base64Url input.\n\n## Announcement\n\nAnnouncement for this issue can be found at https://github.com/dotnet/announcements/issues/384\n\n## CVSS Details\n\n- **Version:** 3.1\n- **Score:** 7.5\n- **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`\n- **Severity:** High\n- **Weakness:** CWE-129 (Improper Validation of Array Index); CWE-125 (Out-of-bounds Read)\n\n## Affected Platforms\n\n- **Platforms:** All\n- **Architectures:** All\n\n## Affected Products\n\n### <a name=\".NET 9\"></a>.NET 9\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\".NET 10\"></a>.NET 10\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"Micorsoft.Bcl.Memory 9.0.14\"></a>Micorsoft.Bcl.Memory 9.0.14\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\"Micorsoft.Bcl.Memory 10.0.4\"></a>Micorsoft.Bcl.Memory 10.0.4\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"how-fix\"></a>How do I fix the issue?\n\nTo update the Microsoft.Bcl.Memory NuGet package, use one of the following methods:\n\nNuGet Package Manager UI in Visual Studio:\n- Open your project in Visual Studio.\n- Right-click on your project in Solution Explorer and select \"Manage NuGet Packages...\" or navigate to \"Project > Manage NuGet Packages\".\n- In the NuGet Package Manager window, select the \"Updates\" tab. This tab lists packages with available updates from your configured package sources.\n- Select the package(s) you wish to update. You can choose a specific version from the dropdown or update to the latest available version.\n- Click the \"Update\" button.\n\nUsing the NuGet Package Manager Console in Visual Studio:\n- Open your project in Visual Studio.\n- Navigate to \"Tools > NuGet Package Manager > Package Manager Console\".\n- To update a specific package to its latest version, use the following Update-Package command:\n\n```Update-Package -Id Microsoft.Bcl.Memory```\n\nUsing the .NET CLI (Command Line Interface):\n- Open a terminal or command prompt in your project's directory.\n- To update a specific package to its latest version, use the following add package command:\n\n```dotnet package update Microsoft.Bcl.Memory```\n\nOnce you have updated the nuget package reference you must recompile and deploy your application. Additionally we recommend you update your runtime and/or SDKs, but unless you are targeting .NET 9 or higher, updating your runtime and/or SDK is not a required step to patch this vulnerability.\n\n## Other Information\n\n### Reporting Security Issues\n\nIf 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](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue).\n\nSecurity 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.\n\n### Support\n\nYou 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.\n\n### Disclaimer\n\nThe 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.\n\n### External Links\n\n[CVE-2026-26127](https://www.cve.org/CVERecord?id=CVE-2026-26127)\n\n### Revisions\n\nV1.0 (March 10, 2026): Advisory published.",
"details": "# Microsoft Security Advisory CVE-2026-26127 – .NET Denial of Service Vulnerability\n\n## Executive summary\n\nMicrosoft 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.\n\nA denial of service vulnerability exists in .NET and Microsoft.Bcl.Memory due to an out-of-bounds read when decoding malformed Base64Url input.\n\n## Announcement\n\nAnnouncement for this issue can be found at https://github.com/dotnet/announcements/issues/384\n\n## CVSS Details\n\n- **Version:** 3.1\n- **Score:** 7.5\n- **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`\n- **Severity:** High\n- **Weakness:** CWE-129 (Improper Validation of Array Index); CWE-125 (Out-of-bounds Read)\n\n## Affected Platforms\n\n- **Platforms:** All\n- **Architectures:** All\n\n## Affected Products\n\n### <a name=\".NET 9\"></a>.NET 9\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.13 | 9.0.14\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\".NET 10\"></a>.NET 10\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 10.0.0, <= 10.0.3 | 10.0.4\n[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"Microsoft.Bcl.Memory 9.0.14\"></a>Microsoft.Bcl.Memory 9.0.14\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 9.0.0, <= 9.0.13 | 9.0.14\n\n### <a name=\"Microsoft.Bcl.Memory 10.0.4\"></a>Microsoft.Bcl.Memory 10.0.4\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.Bcl.Memory](https://www.nuget.org/packages/Microsoft.Bcl.Memory) | >= 10.0.0, <= 10.0.3 | 10.0.4\n\n### <a name=\"how-fix\"></a>How do I fix the issue?\n\nTo update the Microsoft.Bcl.Memory NuGet package, use one of the following methods:\n\nNuGet Package Manager UI in Visual Studio:\n- Open your project in Visual Studio.\n- Right-click on your project in Solution Explorer and select \"Manage NuGet Packages...\" or navigate to \"Project > Manage NuGet Packages\".\n- In the NuGet Package Manager window, select the \"Updates\" tab. This tab lists packages with available updates from your configured package sources.\n- Select the package(s) you wish to update. You can choose a specific version from the dropdown or update to the latest available version.\n- Click the \"Update\" button.\n\nUsing the NuGet Package Manager Console in Visual Studio:\n- Open your project in Visual Studio.\n- Navigate to \"Tools > NuGet Package Manager > Package Manager Console\".\n- To update a specific package to its latest version, use the following Update-Package command:\n\n```Update-Package -Id Microsoft.Bcl.Memory```\n\nUsing the .NET CLI (Command Line Interface):\n- Open a terminal or command prompt in your project's directory.\n- To update a specific package to its latest version, use the following add package command:\n\n```dotnet package update Microsoft.Bcl.Memory```\n\nOnce you have updated the nuget package reference you must recompile and deploy your application. Additionally we recommend you update your runtime and/or SDKs, but unless you are targeting .NET 9 or higher, updating your runtime and/or SDK is not a required step to patch this vulnerability.\n\n## Other Information\n\n### Reporting Security Issues\n\nIf 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](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue).\n\nSecurity 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.\n\n### Support\n\nYou 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.\n\n### Disclaimer\n\nThe 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.\n\n### External Links\n\n[CVE-2026-26127](https://www.cve.org/CVERecord?id=CVE-2026-26127)\n\n### Revisions\n\nV1.0 (March 10, 2026): Advisory published.",

Copilot uses AI. Check for mistakes.
Copy link

Copilot AI Mar 12, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The fenced code blocks in the details string are written as Update-Package -Id ... / dotnet ... on a single line. In Markdown this is interpreted as a fence with a (very long) language identifier and an empty code block, so the commands may not render correctly. Please switch to standard fenced blocks with the command on its own line between opening/closing backticks (matching other advisories in this repo).

Copilot uses AI. Check for mistakes.
"severity": [
{
"type": "CVSS_V3",
Expand Down
Loading