# CVE-2020-1161: ASP.NET Core Denial of Service Vulnerability > Remote unauthenticated attackers can cause denial of service in ASP.NET Core applications by sending specially crafted web requests. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 21 May 2020 - **Updated:** 19 Aug 2026 - **Also known as:** BIT-aspnet-core-2020-1161, GHSA-3cf7-7wq6-8842 ## What is CVE-2020-1161? CVE-2020-1161 is a high-severity denial of service vulnerability in Microsoft Visual Studio 2017, published on 21 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official 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. ## Which versions are affected by CVE-2020-1161? 19 open source packages ship an affected version, including Microsoft.AspNetCore.App.Runtime.linux-arm, aspnet-core and Microsoft.AspNetCore.App.Runtime.linux-arm64. It affects 3 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `Microsoft.AspNetCore.App.Runtime.linux-arm` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-arm` | NuGet | From 3.1.0 | 3.1.4 | | `aspnet-core` | Bitnami | From 3.1.0 | 3.1.1 | | `Microsoft.AspNetCore.App.Runtime.linux-arm64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-arm64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-musl-arm64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-musl-arm64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-musl-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-musl-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.linux-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.osx-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.osx-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.win-arm` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.win-arm` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.win-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.win-x64` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.win-x86` | NuGet | From 3.1.0 | 3.1.4 | | `Microsoft.AspNetCore.App.Runtime.win-x86` | NuGet | From 3.1.0 | 3.1.4 | Products: Microsoft Asp.net Core, Microsoft Visual Studio 2017, Microsoft Visual Studio 2019. ## How do I fix CVE-2020-1161? Upgrade Microsoft.AspNetCore.App.Runtime.linux-arm to 3.1.4 or later. ## Is CVE-2020-1161 being exploited? There is no known exploitation of CVE-2020-1161 in the wild and no public exploit code. ## Other vulnerabilities in Microsoft Visual Studio 2017 - [CVE-2025-55315](https://insights.sbomify.com/CVE-2025-55315/): ASP.NET Security Feature Bypass Vulnerability (critical 9.9) - [CVE-2026-88092](https://insights.sbomify.com/CVE-2026-88092/): ASP.NET Core Tampering Vulnerability (critical 9.4) - [CVE-2026-40372](https://insights.sbomify.com/CVE-2026-40372/): ASP.NET Core Elevation of Privilege Vulnerability (critical 9.1) - [CVE-2021-43877](https://insights.sbomify.com/CVE-2021-43877/): ASP.NET Core and Visual Studio Elevation of Privilege Vulnerability (high 8.8) - [CVE-2020-0603](https://insights.sbomify.com/CVE-2020-0603/): Remote code execution in ASP.NET Core (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-1161 and fix it if it is affected. What it is: CVE-2020-1161 is a high-severity denial of service vulnerability in Microsoft Visual Studio 2017, published on 21 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2020-1161 in the wild and no public exploit code. Affected packages and fixed versions: - Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 3.1.0; fixed in 3.1.4 - aspnet-core (Bitnami): affected from 3.1.0; fixed in 3.1.1 - Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet): affected from 3.1.0; fixed in 3.1.4 - Microsoft.AspNetCore.App.Runtime.osx-x64 (NuGet): affected from 3.1.0; fixed in 3.1.4 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2020-1161/ (Markdown: https://insights.sbomify.com/CVE-2020-1161/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1161 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1161 - OSV: https://osv.dev/vulnerability/CVE-2020-1161 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-1161/ Summaries are generated and may contain mistakes; the official description above is the record.