When used as a producer, the CXFRS component's org.apache.camel.component.cxf.jaxrs.CxfRsProducer#populateCxfRsProducerException method converts the received HTTP response status code to text:
String statusText = Response.Status.fromStatusCode(responseCode).toString();
If the JAX-RS-supplied fromStatusCode method does not recognize the status code provided, it returns null, causing the CxfRsProducer to throw an NPE.
Note that Response.Status does not encompass all response codes. I ran afoul of this when a REST service returned a 422 for a validation error.
I will attach a unit test that illustrates this problem, as a patch to the current unit tests for the class.