Summary
Default development error handler in Ratpack is vulnerable to HTML content injection (XSS)
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);
}));
});
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
Impact
- Cross-Site Scripting
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2019-10770 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.7.6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This vulnerability has been patched in Ratpack version 1.7.6.
Frequently Asked Questions
- What is CVE-2019-10770? CVE-2019-10770 is a medium-severity cross-site scripting (XSS) vulnerability in io.ratpack:ratpack-core (maven), affecting versions < 1.7.6. It is fixed in 1.7.6. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2019-10770? CVE-2019-10770 has a CVSS score of 6.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of io.ratpack:ratpack-core are affected by CVE-2019-10770? io.ratpack:ratpack-core (maven) versions < 1.7.6 is affected.
- Is there a fix for CVE-2019-10770? Yes. CVE-2019-10770 is fixed in 1.7.6. Upgrade to this version or later.
- Is CVE-2019-10770 exploitable, and should I be worried? Whether CVE-2019-10770 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2019-10770 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2019-10770? Upgrade
io.ratpack:ratpack-coreto 1.7.6 or later.