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CVE-2026-109478VulnerabilityPublished

Microsoft.AspNetCore.App.Runtime.linux arm: Microsoft Security Advisory CVE-2026-109478 - ASP.NET Core Denial of

Affects Microsoft.AspNetCore.App.Runtime.linux-armSource GCVE Database

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Authoritative record:CVE-2026-109478· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 8.0.34 soon.

Data as of 11 Nov 2026, 01:50 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (microsoft)CVSS 3.17.5
Patch
Available – fixed in 8.0.34, 9.0.0-preview.4.24267.6
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade Microsoft.AspNetCore.App.Runtime.linux-arm and Microsoft.AspNetCore.App.Runtime.linux-arm64 and Microsoft.AspNetCore.App.Runtime.linux-musl-arm and Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 and Microsoft.AspNetCore.App.Runtime.linux-musl-x64 and Microsoft.AspNetCore.App.Runtime.linux-x64 and Microsoft.AspNetCore.App.Runtime.osx-arm64 and Microsoft.AspNetCore.App.Runtime.osx-x64 and Microsoft.AspNetCore.App.Runtime.win-arm64 and Microsoft.AspNetCore.App.Runtime.win-x64 and Microsoft.AspNetCore.App.Runtime.win-x86 to 8.0.34; Microsoft.AspNetCore.App.Runtime.linux-arm and Microsoft.AspNetCore.App.Runtime.linux-arm64 and Microsoft.AspNetCore.App.Runtime.linux-musl-arm and Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 and Microsoft.AspNetCore.App.Runtime.linux-musl-x64 and Microsoft.AspNetCore.App.Runtime.linux-x64 and Microsoft.AspNetCore.App.Runtime.osx-arm64 and Microsoft.AspNetCore.App.Runtime.osx-x64 and Microsoft.AspNetCore.App.Runtime.win-arm64 and Microsoft.AspNetCore.App.Runtime.win-x64 and Microsoft.AspNetCore.App.Runtime.win-x86 to 9.0.0-preview.4.24267.6.

Affected software

ProductAffectedFixed in
NuGetMicrosoft.AspNetCore.App.Runtime.linux-armAffected
  • >=8.0.0-preview.1.23112.2 <8.0.34
Fixed in
  • 8.0.34
NuGetMicrosoft.AspNetCore.App.Runtime.linux-arm64Affected
  • >=8.0.0-preview.1.23112.2 <8.0.34
Fixed in
  • 8.0.34
NuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-armAffected
  • >=8.0.0-preview.1.23112.2 <8.0.34
Fixed in
  • 8.0.34
NuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-arm64Affected
  • >=8.0.0-preview.1.23112.2 <8.0.34
Fixed in
  • 8.0.34
NuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-x64Affected
  • >=8.0.0-preview.1.23112.2 <8.0.34
Fixed in
  • 8.0.34
NuGetMicrosoft.AspNetCore.App.Runtime.linux-x64Affected
  • >=8.0.0-preview.1.23112.2 <8.0.34
Fixed in
  • 8.0.34

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Apply the official patches provided by Microsoft. Upgrade affected Microsoft.AspNetCore.App.Runtime packages to version 8.0.34 or later for .NET 8.0, and to 9.0.0-preview.4.24267.6 or later for .NET 9.0 previews. No other mitigation or workaround is indicated by the vendor advisory.

Description

A vulnerability in ASP.NET Core allows processing of comma-separated HTTP header values to cause excessive memory allocations leading to resource exhaustion. This denial of service issue affects multiple platforms and architectures. The flaw is tracked as CVE-2026-109478 with a CVSS 3.1 base score of 7.5 (high severity). Fixed versions have been released for affected runtime packages in .NET 8.0 and 9.0.

References

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