A Polymorphic Typing issue was discovered in FasterXML jackson-databind 2.x before 2.9.9. When Default Typing is enabled (either globally or for a specific property) for an externally exposed JSON endpoint, the service has the mysql-connector-java jar (8.0.14 or earlier) in the classpath, and an attacker can host a crafted MySQL server reachable by the victim, an attacker can send a crafted JSON message that allows them to read arbitrary local files on the server. This occurs because of missing com.mysql.cj.jdbc.admin.MiniAdmin validation.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Jackson-databind | Fasterxml | 2.0.0 (including) | 2.6.7.3 (excluding) |
| Jackson-databind | Fasterxml | 2.7.0 (including) | 2.7.9.6 (excluding) |
| Jackson-databind | Fasterxml | 2.8.0 (including) | 2.8.11.4 (excluding) |
| Jackson-databind | Fasterxml | 2.9.0 (including) | 2.9.9 (excluding) |
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.