GHSA-9V76-4QCC-FRGH
Vulnerability from github – Published: 2026-05-18 19:10 – Updated: 2026-05-18 19:10
VLAI
Summary
Microsoft Security Advisory CVE-2026-42899 – ASP.NET Core Denial of Service Vulnerability
Details
Executive Summary:
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 8.0, .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.
Loop with unreachable exit condition ('infinite loop') in ASP.NET Core allows an unauthorized attacker to deny service over a network.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/397
CVSS Details
- Version: 3.1
- Severity:
- Score: 7.5
- Vector: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
- Weakness: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Platforms
- Platforms: All
- Architectures: All
Affected Packages
The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below
.NET 10
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.AspNetCore.App.Runtime.win-arm | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.linux-arm | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.linux-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.linux-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.osx-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.AspNetCore.App.Runtime.osx-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
.NET 9
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.AspNetCore.App.Runtime.win-arm | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.linux-arm | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.linux-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.linux-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.osx-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.AspNetCore.App.Runtime.osx-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
.NET 8
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.AspNetCore.App.Runtime.win-arm | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.win-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.win-x86 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.linux-arm | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.linux-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.linux-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.osx-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.AspNetCore.App.Runtime.osx-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
Advisory FAQ
How do I know if I am affected?
If using a package listed in affected packages, an application is exposed to the vulnerability.
How do I fix the issue?
- To fix the issue please install the latest version of .NET 8.0, NET 9.0, or .NET 10.0, as appropriate. If developers have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt them to update Visual Studio, which will also update the application's .NET SDKs.
- If an application references the vulnerable package, update the package reference to the patched version. Developers can list the versions they have installed by running the
dotnet --infocommand.
Once developers have installed the updated runtime or SDK, they should restart their apps for the update to take effect.
Additionally, if developers have deployed self-contained applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.
Other Information
Reporting Security Issues
If a potential security issue has been found 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
Questions about this issue can be submitted to 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. Questions can be submitted through 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
Acknowledgements
hamayanhamayan Muhammad Abdul Rehman
Revisions
V1.0 (May 12, 2026): Advisory published.
Severity
7.5 (High)
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},
"details": "## Executive Summary: \n\nMicrosoft is releasing this security advisory to provide information about a vulnerability in .NET 8.0, .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\nLoop with unreachable exit condition (\u0027infinite loop\u0027) in ASP.NET Core allows an unauthorized attacker to deny service over a network.\n\n## Announcement\n\nAnnouncement for this issue can be found at https://github.com/dotnet/announcements/issues/397\n\n## CVSS Details\n\n- **Version:** 3.1\n- **Severity:** \n- **Score:** 7.5\n- **Vector:** AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C \n- **Weakness:** CWE-835: Loop with Unreachable Exit Condition (\u0027Infinite Loop\u0027)\n\n## Affected Platforms\n\n- **Platforms:** All\n- **Architectures:** All\n\n## \u003ca name=\"affected-packages\"\u003e\u003c/a\u003eAffected Packages\nThe vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below\n\n### \u003ca name=\".NET 10\"\u003e\u003c/a\u003e.NET 10\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.AspNetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x86) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-x64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-x64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-arm64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n[Microsoft.AspNetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-x64) | \u003e= 10.0.0, \u003c= 10.0.7 | 10.0.8\n\n### \u003ca name=\".NET 9\"\u003e\u003c/a\u003e.NET 9\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.AspNetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x86) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-x64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-x64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-arm64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n[Microsoft.AspNetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-x64) | \u003e= 9.0.0, \u003c= 9.0.15 | 9.0.16\n\n\n### \u003ca name=\".NET 8\"\u003e\u003c/a\u003e.NET 8\nPackage name | Affected version | Patched version\n------------ | ---------------- | -------------------------\n[Microsoft.AspNetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-arm64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.win-x86) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-x64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-x64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-arm64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n[Microsoft.AspNetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.osx-x64) | \u003e= 8.0.0, \u003c= 8.0.26 | 8.0.27\n\n## Advisory FAQ\n\n### \u003ca name=\"how-affected\"\u003e\u003c/a\u003eHow do I know if I am affected?\n\nIf using a package listed in [affected packages](#affected-packages), an application is exposed to the vulnerability.\n\n### \u003ca name=\"how-fix\"\u003e\u003c/a\u003eHow do I fix the issue?\n\n1. To fix the issue please install the latest version of .NET 8.0, NET 9.0, or .NET 10.0, as appropriate. If developers have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt them to update Visual Studio, which will also update the application\u0027s .NET SDKs.\n2. If an application references the vulnerable package, update the package reference to the patched version. Developers can list the versions they have installed by running the `dotnet --info` command. \n\nOnce developers have installed the updated runtime or SDK, they should restart their apps for the update to take effect.\n\nAdditionally, if developers have deployed [self-contained applications](https://docs.microsoft.com/dotnet/core/deploying/#self-contained-deployments-scd) targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.\n\n## Other Information\n\n### Reporting Security Issues\n\nIf a potential security issue has been found 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\nQuestions about this issue can be submitted to 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. Questions can be submitted through 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-2026-42899]( https://www.cve.org/CVERecord?id=CVE-2026-42899)\n\n### Acknowledgements\nhamayanhamayan\u202fMuhammad Abdul Rehman \n\n### Revisions\n\nV1.0 (May 12, 2026): Advisory published.",
"id": "GHSA-9v76-4qcc-frgh",
"modified": "2026-05-18T19:10:59Z",
"published": "2026-05-18T19:10:59Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/dotnet/aspnetcore/security/advisories/GHSA-9v76-4qcc-frgh"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42899"
},
{
"type": "WEB",
"url": "https://github.com/dotnet/announcements/issues/397"
},
{
"type": "PACKAGE",
"url": "https://github.com/dotnet/aspnetcore"
},
{
"type": "WEB",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42899"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Microsoft Security Advisory CVE-2026-42899 \u2013 ASP.NET Core Denial of Service Vulnerability"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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