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Fencer Intel
high 7.5

CVE-2026-109478 json

ASP.NET Core Denial of Service Vulnerability

published yesterday modified 17h ago also EUVD-2026-121561 , GHSA-r3qf-p3jm-8h4p

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

Summary

Inefficient algorithmic complexity in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Patch / fix

  • nuget Microsoft.AspNetCore.App.Runtime.linux-arm 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.linux-arm64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.linux-musl-arm 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.linux-musl-x64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.linux-x64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.osx-arm64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.osx-x64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.win-arm64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.win-x64 8.0.34, 9.0.0-preview.4.24267.6
  • nuget Microsoft.AspNetCore.App.Runtime.win-x86 8.0.34, 9.0.0-preview.4.24267.6
  • Microsoft .NET 8.0 installed on Linux 8.0.34
  • Microsoft .NET 8.0 installed on Mac OS 8.0.34
  • Microsoft .NET 8.0 installed on Windows 8.0.34
  • Microsoft .NET 9.0 installed on Linux 9.0.0-preview.4.24266.19
  • Microsoft .NET 9.0 installed on Mac OS 9.0.0-preview.4.24266.19
  • Microsoft .NET 9.0 installed on Windows 9.0.0-preview.4.24266.19
  • Microsoft Microsoft Visual Studio 2022 version 17.14 17.14.45
  • Microsoft Microsoft Visual Studio 2026 version 18.11 18.11.4

Is CVE-2026-109478 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-109478 updated cvss 7.5

dotnet8.0: ASP.NET Core Denial of Service Vulnerability

  • Red Hat Enterprise Linux AppStream (v. 8) dotnet8.0 8.0.134-1.el8_10, dotnet-sdk-8.0 8.0.134-1.el8_10, dotnet-hostfxr-8.0 8.0.34-1.el8_10, dotnet-runtime-8.0 8.0.34-1.el8_10, dotnet-sdk-dbg-8.0 8.0.134-1.el8_10, dotnet-templates-8.0 8.0.134-1.el8_10, +6 more
    fixed: vendor fix RHSA-2026:99052
  • Red Hat Enterprise Linux AppStream (v. 9) dotnet8.0 8.0.134-1.el9_9, dotnet-sdk-8.0 8.0.134-1.el9_9, dotnet-hostfxr-8.0 8.0.34-1.el9_9, dotnet-runtime-8.0 8.0.34-1.el9_9, dotnet-sdk-dbg-8.0 8.0.134-1.el9_9, dotnet-templates-8.0 8.0.134-1.el9_9, +6 more
    fixed: vendor fix RHSA-2026:99146
  • Red Hat Enterprise Linux AppStream (v. 10) dotnet8.0 8.0.134-1.el10_3, dotnet-sdk-8.0 8.0.134-1.el10_3, dotnet-hostfxr-8.0 8.0.34-1.el10_3, dotnet-runtime-8.0 8.0.34-1.el10_3, dotnet-sdk-dbg-8.0 8.0.134-1.el10_3, dotnet-templates-8.0 8.0.134-1.el10_3, +6 more
    fixed: vendor fix RHSA-2026:99147
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) dotnet-sdk-8.0-source-built-artifacts 8.0.134-1.el9_9
    fixed: vendor fix RHSA-2026:99146
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) dotnet-sdk-8.0-source-built-artifacts 8.0.134-1.el10_3
    fixed: vendor fix RHSA-2026:99147
  • Red Hat Enterprise Linux CRB (v. 8) dotnet-sdk-8.0-source-built-artifacts 8.0.134-1.el8_10
    fixed: vendor fix RHSA-2026:99052
  • Red Hat Hardened Images dotnet8.0 8.0.133-0.1.hum1
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
yesterday

Exploit prediction

1.25% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 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
GitHub 3.1 7.5 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
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
nuget Microsoft.AspNetCore.App.Runtime.linux-arm
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.linux-arm64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.linux-musl-arm
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.linux-musl-arm64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.linux-musl-x64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.linux-x64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.osx-arm64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.osx-x64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.win-arm64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.win-x64
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6
nuget Microsoft.AspNetCore.App.Runtime.win-x86
>=8.0.0-preview.1.23112.2, <8.0.34
>=9.0.0-preview.1.24081.5, <9.0.0-preview.4.24267.6
>=9.0.0-preview.2.24128.4, <9.0.0-preview.4.24267.6
>=9.0.0-preview.3.24172.13, <9.0.0-preview.4.24267.6
8.0.34
9.0.0-preview.4.24267.6

Affected products

  • Microsoft .NET 8.0 installed on Linux
  • Microsoft .NET 8.0 installed on Mac OS
  • Microsoft .NET 8.0 installed on Windows
  • Microsoft .NET 9.0 installed on Linux
  • Microsoft .NET 9.0 installed on Mac OS
  • Microsoft .NET 9.0 installed on Windows
  • Microsoft Microsoft Visual Studio 2022 version 17.14
  • Microsoft Microsoft Visual Studio 2026 version 18.11
  • Microsoft Microsoft Visual Studio 2026 version 18.12

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.