Advisories for Maven/Org.eclipse.californium/Californium-Core package

Eclipse Californium is a Java implementation of RFC7252 - Constrained Application Protocol for IoT Cloud services. In versions prior to 3.7.0, and 2.7.4, Californium is vulnerable to a Denial of Service. Failing handshakes don't cleanup counters for throttling, causing the threshold to be reached without being released again. This results in permanently dropping records. The issue was reported for certificate based handshakes, but may also affect PSK based handshakes. It …

In Eclipse Californium version 2.0.0 to 2.7.2 and 3.0.0-3.5.0 a DTLS resumption handshake falls back to a DTLS full handshake on a parameter mismatch without using a HelloVerifyRequest. Especially, if used with certificate based cipher suites, that results in message amplification (DDoS other peers) and high CPU load (DoS own peer). The misbehavior occurs only with DTLS_VERIFY_PEERS_ON_RESUMPTION_THRESHOLD values larger than 0.

In Eclipse Californium the certificate based (x509 and RPK) DTLS handshakes accidentally succeeds without verifying the server side's signature on the client side, if that signature is not included in the server's ServerKeyExchange.

In Eclipse Californium to, the certificate based (x509 and RPK) DTLS handshakes accidentally fails, because the DTLS server side sticks to a wrong internal state. That wrong internal state is set by a previous certificate based DTLS handshake failure with TLS parameter mismatch. The DTLS server side must be restarted to recover this.