CVE-2020-0603 — Microsoft.AspNetCore.All
HIGHCVE-2020-0603 is a high-severity (CVSS 8.8) Out-of-bounds Write vulnerability in Microsoft.AspNetCore.All. EPSS puts its 30-day exploitation probability at 21.0% (97th percentile). A fix is available for Microsoft.AspNetCore.All — see the affected versions and patch details below.
Remote code execution in ASP.NET Core
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2020-0603 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
Microsoft.AspNetCore.All.NETMicrosoft.AspNetCore.App.NETMicrosoft.AspNetCore.App.NETMicrosoft.AspNetCore.App.NETMicrosoft.AspNetCore.Http.Connections.NETMicrosoft.AspNetCore.App.Runtime.linux-arm.NETMicrosoft.AspNetCore.App.Runtime.linux-arm64.NETMicrosoft.AspNetCore.App.Runtime.linux-musl-arm64+6 moreReal-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 remote code execution vulnerability exists in ASP.NET Core software when the software fails to handle objects in memory.An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the current user, aka 'ASP.NET Core Remote Code Execution Vulnerability'.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.AspNetCore.All | ≥ 2.1.0&&< 2.1.15 | 2.1.15dotnet add package Microsoft.AspNetCore.All --version 2.1.15 |
| .NETNuGet | Microsoft.AspNetCore.App | ≥ 3.1.0&&< 3.1.1 | 3.1.1dotnet add package Microsoft.AspNetCore.App --version 3.1.1 |
| .NETNuGet | Microsoft.AspNetCore.App | ≥ 3.0.0&&< 3.0.1 | 3.0.1dotnet add package Microsoft.AspNetCore.App --version 3.0.1 |
| .NETNuGet | Microsoft.AspNetCore.App | ≥ 2.1.0&&< 2.1.15 | 2.1.15dotnet add package Microsoft.AspNetCore.App --version 2.1.15 |
| .NETNuGet | Microsoft.AspNetCore.Http.Connections | ≥ 1.0.0&&< 1.0.15 | 1.0.15dotnet add package Microsoft.AspNetCore.Http.Connections --version 1.0.15 |
| .NETNuGet | Microsoft.AspNetCore.App.Runtime.linux-arm | ≥ 3.1.0&&< 3.1.1 | 3.1.1dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm --version 3.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.All, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.AspNetCore.All to 2.1.15 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-0603 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2020-0603 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-0603. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
| Product | Fixed in | Advisory |
|---|---|---|
| .NET Core on Red Hat Enterprise Linux | rh-dotnet30-dotnet-0:3.0.102-3.el7 | RHSA-2020:0134 |
| Red Hat Enterprise Linux 8 | dotnet3.0-0:3.0.102-2.el8_1 | RHSA-2020:0130 |
Frequently Asked Questions
Is CVE-2020-0603 in your dependencies?
O3 Security finds CVE-2020-0603 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.