Version 10.11 of webMethods OneData runs an embedded instance of Azul Zulu Java 11.0.15 which hosts a Java RMI registry (listening on TCP port 2099 by default) and two RMI interfaces (listening on a single, dynamically assigned TCP high port). Port 2099 serves as a Java Remote Method Invocation (RMI) registry which allows for remotely loading and processing data via RMI interfaces. An unauthenticated attacker with network connectivity to the RMI registry and RMI interface ports can abuse this functionality to instruct the webMethods OneData application to load a malicious serialized Java object as a parameter to one of the available Java methods presented by the RMI interface. Once deserialized on the vulnerable server, the malicious code runs as whichever operating system account is used to run the software, which in most cases is the local System account on Windows.
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.