CVE-2019-10770 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in io.ratpack:ratpack-core. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2019-10770 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Default development error handler in Ratpack is vulnerable to HTML content injection (XSS)
Real-World Exposure
io.ratpack:ratpack-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Versions of Ratpack from 0.9.10 through 1.7.5 are vulnerable to CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (aka. XSS) in the development error handler. An attacker can utilize this to perform XSS when an exception message contains untrusted data.
As a simplistic example:
RatpackServer startedServer = RatpackServer.start(server -> {
server.handlers(chain -> chain.all(ctx -> {
// User supplied query parameter
String message = ctx.getRequest().getQueryParams().get("message");
// User supplied data appended to the message in an exception
throw new RuntimeException("An error occurred: " + message);
}));
});
Impact
- Cross-Site Scripting
Patches
This vulnerability has been patched in Ratpack version 1.7.6.
Workarounds
If you are unable to update your version of Ratpack, we recommend the following workarounds and mitigations.
- Ensure that development mode is disabled in production.
- Don't use real customer data (ie. untrusted user input) in development.
References
For more information
If you have any questions or comments about this advisory:
- Open an issue in ratpack/ratpack
- Ask in our Slack channel
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.ratpack:ratpack-core | all versions | 1.7.6 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.ratpack:ratpack-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update io.ratpack:ratpack-core to 1.7.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-10770 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 pinpoints whether CVE-2019-10770 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2019-10770. 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-2019-10770 in your dependencies?
O3 detects CVE-2019-10770 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.