CVE-2017-11883 — Microsoft.AspNetCore.Serv…
HIGHCVE-2017-11883 is a high-severity (CVSS 7.5) vulnerability in Microsoft.AspNetCore.Server.WebListener. A fix is available for Microsoft.AspNetCore.Server.WebListener — see the affected versions and patch details below.
Denial of service 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-2017-11883 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% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
Microsoft.AspNetCore.Server.WebListener.NETMicrosoft.AspNetCore.Server.WebListener.NETMicrosoft.Net.Http.Server.NETMicrosoft.Net.Http.Server.NETMicrosoft.AspNetCore.Server.HttpSysReal-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
.NET Core 1.0, 1.1, and 2.0 allow an unauthenticated attacker to remotely cause a denial of service attack against a .NET Core web application by improperly handling web requests, aka ".NET CORE Denial Of Service Vulnerability".
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.AspNetCore.Server.WebListener | ≥ 1.0.0&&< 1.0.6 | 1.0.6dotnet add package Microsoft.AspNetCore.Server.WebListener --version 1.0.6 |
| .NETNuGet | Microsoft.AspNetCore.Server.WebListener | ≥ 1.1.0&&< 1.1.4 | 1.1.4dotnet add package Microsoft.AspNetCore.Server.WebListener --version 1.1.4 |
| .NETNuGet | Microsoft.Net.Http.Server | ≥ 1.0.0&&< 1.0.6 | 1.0.6dotnet add package Microsoft.Net.Http.Server --version 1.0.6 |
| .NETNuGet | Microsoft.Net.Http.Server | ≥ 1.1.0&&< 1.1.4 | 1.1.4dotnet add package Microsoft.Net.Http.Server --version 1.1.4 |
| .NETNuGet | Microsoft.AspNetCore.Server.HttpSys | ≥ 2.0.0&&< 2.0.2 | 2.0.2dotnet add package Microsoft.AspNetCore.Server.HttpSys --version 2.0.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.Server.WebListener, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.AspNetCore.Server.WebListener to 1.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-11883 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-2017-11883 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2017-11883. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2017-11883 in your dependencies?
O3 Security finds CVE-2017-11883 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.