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Vulnerability · CVE-2026-70186

Microsoft Security Advisory CVE-2026-70186 - ASP.NET Core Denial of Service Vulnerability

Published Oct 13, 2026 · catalog updated Oct 13, 2026 · Microsoft ASP.NET Core 10.0

Check if you run it

No confirmed exploitation is on record for CVE-2026-70186. EPSS is 0.85%. Act only if a listed version of Microsoft ASP.NET Core 10.0 is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.85%
Remediation
Version ranges on file
Affected products
NuGet Microsoft.AspNetCore.App.Runtime.linux-arm · NuGet Microsoft.AspNetCore.App.Runtime.linux-arm64 · NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-arm · NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 · NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-x64 · NuGet Microsoft.AspNetCore.App.Runtime.linux-x64

## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Server.Kestrel.Core. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. An unauthenticated remote attacker can send crafted HTTP/3 reset or abort sequences that deadlock Kestrel connection handling. Repeated requests can cause excessive blocked-thread creation and exhaust server resources, resulting in denial of service. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/461 ## CVSS Details - **Version:** 3.1 - **Severity:** High - **Score:** 7.5 - **Vector:** - **Weakness:** CWE-833 (Deadlock) ## Affected Platforms - **Platforms:** Windows, Linux, macOS with HTTP/3 support - **Architectures:** All ## Affected Packages The vulnerability affects Microsoft .NET projects that use an affected package version listed below. Package name | Affected version | Patched version ------------ | ---------------- | --------------- [Microsoft.AspNetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm) | >= 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 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, = 10.0.0, = 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, = 9.0.0, How do I know if I am affected? If using a package listed in [affected packages](#affected-packages), you're exposed to the vulnerability. ### How do I fix the issue? 1. To fix the issue please install the latest version of .NET. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs. 2. If your application references the vulnerable package, u

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • NuGet Microsoft.AspNetCore.App.Runtime.linux-arm10.0.0 → 10.0.13
  • NuGet Microsoft.AspNetCore.App.Runtime.linux-arm8.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.linux-arm648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-arm8.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-arm648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-x648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.linux-x648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.osx-arm648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.osx-x648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.win-arm648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.win-x648.0.0 → 8.0.32
  • NuGet Microsoft.AspNetCore.App.Runtime.win-x868.0.0 → 8.0.32
  • nuget Microsoft.AspNetCore.App.Runtime.linux-arm>= 10.0.0, <= 10.0.12
  • nuget Microsoft.AspNetCore.App.Runtime.linux-arm>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.linux-arm64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.linux-musl-arm>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.linux-musl-arm64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.linux-musl-x64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.linux-x64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.osx-arm64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.osx-x64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.win-arm64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.win-x64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.App.Runtime.win-x86>= 8.0.0, <= 8.0.31
  • nuget microsoft.aspnetcore.app.runtime.linux-armversion unspecified
  • nuget microsoft.aspnetcore.app.runtime.linux-arm64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.linux-musl-armversion unspecified
  • nuget microsoft.aspnetcore.app.runtime.linux-musl-arm64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.linux-musl-x64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.linux-x64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.osx-arm64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.osx-x64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.win-arm64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.win-x64version unspecified
  • nuget microsoft.aspnetcore.app.runtime.win-x86version unspecified
  • vendor Microsoft ASP.NET Core 10.0version unspecified

How to fix CVE-2026-70186

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-70186. EPSS is 0.85%. Act only if a listed version of Microsoft ASP.NET Core 10.0 is installed.

Which versions are affected?

Compare what you have installed with Microsoft.AspNetCore.App.Runtime.linux-arm 10.0.0 → 10.0.13; Microsoft.AspNetCore.App.Runtime.linux-arm 8.0.0 → 8.0.32; Microsoft.AspNetCore.App.Runtime.linux-arm64 8.0.0 → 8.0.32; Microsoft.AspNetCore.App.Runtime.linux-musl-arm 8.0.0 → 8.0.32. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-833. EPSS 0.85%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 13, 2026 · Catalog

    Detected

    ## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Server.Kestrel.Core. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. An unauthenticated remote attacker can send crafted HTTP/3 reset or abort sequences that deadlock Kestrel connection hand

  2. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-arm fixed in 8.0.32; Microsoft.AspNetCore.App.Runtime.linux-arm64 fixed in 8.0.32; Microsoft.AspNetCore.App.Runtime.linux-musl-arm fixed in 8.0.32; Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 fixed in 8.0.32

  3. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-arm 8.0.0 → 8.0.32

  4. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-arm64 8.0.0 → 8.0.32

  5. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-arm 8.0.0 → 8.0.32

  6. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 8.0.0 → 8.0.32

  7. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-musl-x64 8.0.0 → 8.0.32

  8. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-x64 8.0.0 → 8.0.32

  9. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.osx-arm64 8.0.0 → 8.0.32

  10. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.osx-x64 8.0.0 → 8.0.32

  11. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.win-arm64 8.0.0 → 8.0.32

  12. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.win-x64 8.0.0 → 8.0.32

  13. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.win-x86 8.0.0 → 8.0.32

  14. Oct 13, 2026 · Catalog

    Fix available

    NuGet Microsoft.AspNetCore.App.Runtime.linux-arm 10.0.0 → 10.0.13

  15. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-arm fixed in 8.0.32

  16. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-arm64 fixed in 8.0.32

  17. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-musl-arm fixed in 8.0.32

  18. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 fixed in 8.0.32

  19. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-musl-x64 fixed in 8.0.32

  20. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-x64 fixed in 8.0.32

  21. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.osx-arm64 fixed in 8.0.32

  22. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.osx-x64 fixed in 8.0.32

  23. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.win-arm64 fixed in 8.0.32

  24. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.win-x64 fixed in 8.0.32

  25. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.win-x86 fixed in 8.0.32

  26. Oct 13, 2026 · GitHub Advisory Database

    Fix available

    Microsoft.AspNetCore.App.Runtime.linux-arm fixed in 10.0.13

  27. Oct 13, 2026 · Catalog

    Updated

    ## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Server.Kestrel.Core. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. An unauthenticated remote attacker can send crafted HTTP/3 reset or abort sequences that deadlock Kestrel connection hand

Sources

  • CVE.orgVulnerability recordCVE-2026-70186

    Deadlock in ASP.NET Core allows an unauthorized attacker to deny service over a network.

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-70186

    30-day exploitation probability 0.8%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-mf4x-w4gh-4656

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-70186

    Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Server.Kestrel.Core. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. An unauthenticated remote attacker can send crafted HTTP/3 reset or abort sequences that deadlock Kestrel connection handling. Repeated reques

    advisories.gitlab.com
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-mf4x-w4gh-4656

    Microsoft Security Advisory CVE-2026-70186 - ASP.NET Core Denial of Service Vulnerability

    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.