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.NET
.NET NuGet
Not in CISA KEV
HIGH severity

CVE-2020-1161 — Microsoft.AspNetCore.App.…

HIGH

CVE-2020-1161 is a high-severity (CVSS 7.5) vulnerability in Microsoft.AspNetCore.App.Runtime.linux-arm. A fix is available for Microsoft.AspNetCore.App.Runtime.linux-arm — see the affected versions and patch details below.

ASP.NET Core Denial of Service Vulnerability

Also known asBIT-aspnet-core-2020-1161GHSA-3cf7-7wq6-8842
Published
Updated
Affected
9 pkgs
Patched
9 / 9
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
5.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk
3.63%4.49%5.34%6.20%4.1%5.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

9 pkgs affected
.NETMicrosoft.AspNetCore.App.Runtime.linux-arm.NETMicrosoft.AspNetCore.App.Runtime.linux-arm64.NETMicrosoft.AspNetCore.App.Runtime.linux-musl-arm64.NETMicrosoft.AspNetCore.App.Runtime.linux-musl-x64.NETMicrosoft.AspNetCore.App.Runtime.linux-x64.NETMicrosoft.AspNetCore.App.Runtime.osx-x64.NETMicrosoft.AspNetCore.App.Runtime.win-arm.NETMicrosoft.AspNetCore.App.Runtime.win-x64+1 more

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

Affected Packages

9 total 9 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetMicrosoft.AspNetCore.App.Runtime.linux-arm≥ 3.1.0&&< 3.1.43.1.4dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm --version 3.1.4
.NETNuGetMicrosoft.AspNetCore.App.Runtime.linux-arm64≥ 3.1.0&&< 3.1.43.1.4dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm64 --version 3.1.4
.NETNuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-arm64≥ 3.1.0&&< 3.1.43.1.4dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 --version 3.1.4
.NETNuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-x64≥ 3.1.0&&< 3.1.43.1.4dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-x64 --version 3.1.4
.NETNuGetMicrosoft.AspNetCore.App.Runtime.linux-x64≥ 3.1.0&&< 3.1.43.1.4dotnet add package Microsoft.AspNetCore.App.Runtime.linux-x64 --version 3.1.4
.NETNuGetMicrosoft.AspNetCore.App.Runtime.osx-x64≥ 3.1.0&&< 3.1.43.1.4dotnet add package Microsoft.AspNetCore.App.Runtime.osx-x64 --version 3.1.4

Affected Products

3 products · 3 configurations
Application
asp.net coremicrosoft
1 version
3.1
Application
visual studio 2017microsoft
≥ 15.1 && ≤ 15.9
range
Application
visual studio 2019microsoft
≥ 16.0 && ≤ 16.5
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.App.Runtime.linux-arm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update Microsoft.AspNetCore.App.Runtime.linux-arm to 3.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-1161 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant
ProductFixed inAdvisory
.NET Core on Red Hat Enterprise Linuxrh-dotnet31-dotnet-0:3.1.104-2.el7RHSA-2020:2249
Red Hat Enterprise Linux 8dotnet3.1-0:3.1.104-2.el8_2RHSA-2020:2250

Frequently Asked Questions

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.
O3 Security · Impact-Aware SCA

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CVE-2020-1161: Microsoft.AspNetCore.App — Fixed in 3.1.4