QID 981602

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')](https://cwe.mitre.org/data/definitions/79.html) (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:
```java
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);
}));
});
```

- Cross-Site Scripting