Prior to 3385, the user-controlled role parameter enters the application in the Kubernetes::RoleVerificationsController. The role parameter flows into the RoleConfigFile initializer and then into the Kubernetes::Util.parse_file method where it is unsafely deserialized using the YAML.load_stream method. This issue may lead to Remote Code Execution (RCE). This vulnerability is fixed in 3385.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.