CVE-2026-109478: ASP.NET Core algorithmic complexity denial of service

CVE-2026-109478 · Severity: high · CVSS 7.5 · Published 2026-11-10

ASP.NET Core, a framework used to build web applications, contains an algorithmic inefficiency that allows an unauthenticated remote attacker to cause a denial of service. An attacker can craft specific requests that consume excessive server resources, rendering the application unresponsive to legitimate users and causing service outages.

Technologies: Microsoft Asp.Net Core, 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 (NuGet), Microsoft.AspNetCore.App.Runtime.osx-arm64 (NuGet), Microsoft.AspNetCore.App.Runtime.osx-x64 (NuGet), Microsoft.AspNetCore.App.Runtime.win-arm64 (NuGet), Microsoft.AspNetCore.App.Runtime.win-x64 (NuGet), Microsoft.AspNetCore.App.Runtime.win-x86 (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is CVE-2026-109478 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-109478 being exploited in the wild.
How severe is CVE-2026-109478?
High severity, with a CVSS score of 7.5, published 10 November 2026.
Which products and versions are affected?
Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet) >= 8.0.0-preview.1.23112.2, <= 8.0.33, ECOSYSTEM:introduced=8.0.0-preview.1.23112.2,fixed=8.0.34; Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet) >= 8.0.0-preview.1.23112.2, <= 8.0.33, ECOSYSTEM:introduced=8.0.0-preview.1.23112.2,fixed=8.0.34; Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet) >= 8.0.0-preview.1.23112.2, <= 8.0.33, ECOSYSTEM:introduced=8.0.0-preview.1.23112.2,fixed=8.0.34; Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet) >= 8.0.0-preview.1.23112.2, <= 8.0.33, ECOSYSTEM:introduced=8.0.0-preview.1.23112.2,fixed=8.0.34; and 7 more.
Is there a fix for CVE-2026-109478?
Yes. Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.osx-arm64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.osx-x64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.win-arm64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.win-x64 (NuGet): upgrade to 8.0.34 or later; Microsoft.AspNetCore.App.Runtime.win-x86 (NuGet): upgrade to 8.0.34 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-109478 attacked?
It is attacked over the network.
Am I affected by CVE-2026-109478?
Check whether you run Microsoft Asp.Net Core, Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet), Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-arm --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-x64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-x64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.osx-arm64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.osx-arm64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.osx-x64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.osx-x64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.win-arm64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.win-arm64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.win-x64 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.win-x64 --version 8.0.34
  • Microsoft.AspNetCore.App.Runtime.win-x86 (NuGet): upgrade to 8.0.34 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.win-x86 --version 8.0.34

Technical details

An inefficient algorithmic complexity flaw in ASP.NET Core allows an unauthenticated attacker to trigger computationally expensive processing via crafted network requests. The vulnerability requires network access but no authentication; exploitation results in denial of service through resource exhaustion. No further details are available from the advisory references.

Affected products

  • Microsoft ASP.NET Core

Identifiers

  • CVE-2026-109478
  • GHSA-r3qf-p3jm-8h4p

Timeline

  • 2026-11-10: disclosed

References

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