Apache Camel CoAP: conversion errors leak internal details to remote clients

Generation of Error Message Containing Sensitive Information vulnerability in Apache Camel CoAP component.

This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.2.

When the CoAP consumer could not build its response once the route had completed, CamelCoapResource caught the resulting exception and sent its message back to the CoAP client as the payload of a 5.00 Internal Server Error response. The typical case is a type conversion failure: the consumer converts the final message body to the byte[] payload, and the CamelCoapMaxAge and CamelCoapETag headers to their types, after the route has returned, and therefore outside the route's error handler. On the affected releases the message of such a failure names the class of the value being converted, carries the value's string form, and ends with the class name and message of the underlying cause, so a remote CoAP client could read internal detail about the deployment: class and package names, the string form of the value, such as the path of a file body, and whatever the cause carries, which in practice can include paths, host names and connection detail of a backend. The consumer had no option to suppress this, unlike the HTTP consumers, which offer a muteException option for that purpose. The exception raised by a failing route was not sent: the consumer did not check whether the exchange had failed, and answered a route failure with 2.05 Content and whatever body the message held at that point. Reaching the disclosure therefore requires a route whose completed response a remote client can make unconvertible, which depends on how the route is written.

Users are recommended to upgrade to version 4.23.0, which fixes the issue. If users are on the 4.22.x releases stream, then they are suggested to upgrade to 4.22.2. If users are on the 4.18.x releases stream, then they are suggested to upgrade to 4.18.5. The 4.14.x releases stream and earlier, and the 4.15.x to 4.17.x and 4.19.x to 4.21.x release lines, reached end of life before this issue was resolved and will not receive a fix, so deployments on them must move to a supported release. The upgrade is enough on its own: the new muteException consumer option defaults to true on all three fixed release lines, so the error response carries no payload without any configuration change. For deployments that cannot upgrade immediately, make sure the response can always be built once the route has completed: convert the body to byte[] or String as the last step of each route that consumes from a coap endpoint, for example with convertBodyTo, give the CamelCoapMaxAge and CamelCoapETag headers only values of their own types, and add an onException handler that marks the failure as handled and sets the response body explicitly, so that a conversion failure is raised and replaced inside the route rather than in the consumer.