Apache James prior to version 3.7.5 and 3.8.0 exposes a JMX endpoint on localhost subject to pre-authentication deserialisation of untrusted data. Given a deserialisation gadjet, this could be leveraged as part of an exploit chain that could result in privilege escalation. Note that by default JMX endpoint is only bound locally.
We recommend users to: - Upgrade to a non-vulnerable Apache James version
- Run Apache James isolated from other processes (docker - dedicated virtual machine) - If possible turn off JMX
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.