CVE-2019-1010199 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in ServiceStack. A fix is available for ServiceStack — see the affected versions and patch details below.
Cross site scripting attack in ServiceStack Framework
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-2019-1010199 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 378,156 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
ServiceStackReal-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
ServiceStack ServiceStack Framework 4.5.14 is affected by: Cross Site Scripting (XSS). The impact is: JavaScrpit is reflected in the server response, hence executed by the browser. The component is: the query used in the GET request is prone. The attack vector is: Since there is no server-side validation and If Browser encoding is bypassed, the victim is affected when opening a crafted URL. The fixed version is: 5.2.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | ServiceStack | ≥ 4.5.14&&< 5.2.0 | 5.2.0dotnet add package ServiceStack --version 5.2.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ServiceStack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ServiceStack to 5.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-1010199 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-2019-1010199 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2019-1010199. 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-2019-1010199 in your dependencies?
O3 Security finds CVE-2019-1010199 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.