CVE-2026-96236: Microsoft ASP.NET Core Localization denial of service

CVE-2026-96236 · Severity: high · CVSS 7.5 · Published 2026-10-13

ASP.NET Core is a web framework used to build and run web applications. A vulnerability in its request localization feature allows unauthenticated attackers to send specially crafted requests that cause unbounded memory growth on the server, leading to denial of service and potential application crashes.

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-2026-96236 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-96236 being exploited in the wild.
How severe is CVE-2026-96236?
High severity, with a CVSS score of 7.5, published 13 October 2026.
Which products and versions are affected?
Microsoft Asp.Net Core 8.0.0 through 8.0.31, 9.0.0 through 9.0.20, 10.0.0 through 10.0.12, 11.0.0-preview.1 through 11.0.0-rc.1; Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet) >= 8.0.0, <= 8.0.31, ECOSYSTEM:introduced=8.0.0,fixed=8.0.32; Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet) >= 8.0.0, <= 8.0.31, ECOSYSTEM:introduced=8.0.0,fixed=8.0.32; Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet) >= 8.0.0, <= 8.0.31, ECOSYSTEM:introduced=8.0.0,fixed=8.0.32; and 8 more.
Is there a fix for CVE-2026-96236?
Yes. Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.osx-arm64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.osx-x64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.win-arm64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.win-x64 (NuGet): upgrade to 8.0.32 or later; Microsoft.AspNetCore.App.Runtime.win-x86 (NuGet): upgrade to 8.0.32 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-96236 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-96236?
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 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-arm --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-x64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.linux-x64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.osx-arm64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.osx-arm64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.osx-x64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.osx-x64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.win-arm64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.win-arm64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.win-x64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.win-x64 --version 8.0.32
  • Microsoft.AspNetCore.App.Runtime.win-x86 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.AspNetCore.App.Runtime.win-x86 --version 8.0.32

Technical details

The vulnerability exists in Microsoft.AspNetCore.Localization request-localization fallback, which unsafely caches attacker-supplied synthetic culture names in the runtime's global cache without limits. An unauthenticated attacker with network access can craft requests with arbitrary culture names to trigger unbounded memory allocation (CWE-770), causing denial of service. Fixed versions are available.

Affected products

  • Microsoft ASP.NET Core 8.0.0 through 8.0.31, 9.0.0 through 9.0.20, 10.0.0 through 10.0.12, 11.0.0-preview.1 through 11.0.0-rc.1

Identifiers

  • CVE-2026-96236
  • GHSA-f4g7-52wc-p8x7

Timeline

  • 2026-10-13: disclosed

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