A Polymorphic Typing issue was discovered in FasterXML jackson-databind 2.x through 2.9.9. When Default Typing is enabled (either globally or for a specific property) for an externally exposed JSON endpoint and the service has JDOM 1.x or 2.x jar in the classpath, an attacker can send a specifically crafted JSON message that allows them to read arbitrary local files on the server.
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.