CVE-2021-26701 .NET Core Remote Code Execution Vulnerability
High 8.1
Published
Updated
Check this codebase for CVE-2021-26701 and fix it if it is affected.
What it is: CVE-2021-26701 is a high-severity code injection vulnerability in Fedoraproject Fedora, published on 25 Feb 2021. 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-2021-26701 in the wild and no public exploit code.
Affected packages and fixed versions:
- System.Text.Encodings.Web (NuGet): affected from 4.0.0; fixed in 4.5.1
- System.Text.Encodings.Web (NuGet): affected from 4.0.0; fixed in 4.5.1
- System.Text.Encodings.Web (NuGet): affected from 4.6.0; fixed in 4.7.2
- System.Text.Encodings.Web (NuGet): affected from 4.6.0; fixed in 4.7.2
- System.Text.Encodings.Web (NuGet): affected from 5.0.0; fixed in 5.0.1
- System.Text.Encodings.Web (NuGet): affected from 5.0.0; fixed in 5.0.1
- dotnet (Bitnami): affected from 5.0.0; fixed in 5.0.4
- dotnet-sdk (Bitnami): affected from 5.0.0; fixed in 5.0.4
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-2021-26701/ (Markdown: https://insights.sbomify.com/CVE-2021-26701/index.md)
Attackers can execute arbitrary code via a vulnerability in the .NET Core runtime, affecting developers and users of .NET applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-26701?
CVE-2021-26701 is a high-severity code injection vulnerability in Fedoraproject Fedora, published on 25 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
.NET Core Remote Code Execution Vulnerability
Which versions are affected by CVE-2021-26701?
8 open source packages ship an affected version, including System.Text.Encodings.Web, dotnet and dotnet-sdk. It affects 5 products.
| Package | Affected | Fixed in |
|---|---|---|
System.Text.Encodings.Web NuGet | From 4.0.0 | 4.5.1 |
System.Text.Encodings.Web NuGet | From 4.0.0 | 4.5.1 |
System.Text.Encodings.Web NuGet | From 4.6.0 | 4.7.2 |
System.Text.Encodings.Web NuGet | From 4.6.0 | 4.7.2 |
System.Text.Encodings.Web NuGet | From 5.0.0 | 5.0.1 |
System.Text.Encodings.Web NuGet | From 5.0.0 | 5.0.1 |
2 more packages
dotnet Bitnami | From 5.0.0 | 5.0.4 |
dotnet-sdk Bitnami | From 5.0.0 | 5.0.4 |
Linux distribution packages (32)
aspnetcore-runtime-3.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
aspnetcore-runtime-5.0 Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
aspnetcore-targeting-pack-3.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
aspnetcore-targeting-pack-5.0 Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.522-1.el8_3 |
dotnet Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.104-1.el8_3 |
dotnet-apphost-pack-3.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
dotnet-apphost-pack-3.1-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
dotnet-apphost-pack-5.0 Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-apphost-pack-5.0-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.522-1.el8_3 |
dotnet-debugsource Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.522-1.el8_3 |
dotnet-host Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-host-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-host-fxr-2.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.26-1.el8_3 |
dotnet-host-fxr-2.1-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.26-1.el8_3 |
dotnet-hostfxr-3.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
dotnet-hostfxr-3.1-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
dotnet-hostfxr-5.0 Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-hostfxr-5.0-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-runtime-2.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.26-1.el8_3 |
dotnet-runtime-2.1-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.26-1.el8_3 |
dotnet-runtime-3.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
dotnet-runtime-3.1-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.13-1.el8_3 |
dotnet-runtime-5.0 Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-runtime-5.0-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.4-1.el8_3 |
dotnet-sdk-2.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.522-1.el8_3 |
dotnet-sdk-2.1.5xx Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.522-1.el8_3 |
dotnet-sdk-2.1.5xx-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:2.1.522-1.el8_3 |
dotnet-sdk-3.1 Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.113-1.el8_3 |
dotnet-sdk-3.1-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:3.1.113-1.el8_3 |
dotnet-sdk-5.0 Red Hat:enterprise_linux:8::appstream | All versions | 0:5.0.104-1.el8_3 |
Products include Fedoraproject Fedora, Microsoft .Net, Microsoft .Net Core, Microsoft Powershell Core, Microsoft Visual Studio 2019.
How do I fix CVE-2021-26701?
Upgrade System.Text.Encodings.Web to a fixed version for your release line: 4.5.1, 4.7.2 or 5.0.1.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2021-26701 being exploited?
There is no known exploitation of CVE-2021-26701 in the wild and no public exploit code.
Other vulnerabilities in Fedoraproject Fedora
Sources
Also known as BIT-dotnet-2021-26701, BIT-dotnet-sdk-2021-26701, ECHO-1fd9-6799-b020, GHSA-ghhp-997w-qr28, RHSA-2021:0787, RHSA-2021:0788 and 4 more.