FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.178, FreeScout is vulnerable to deserialization of untrusted data due to insufficient validation. Through the set function, a string with a serialized object can be passed, and when getting an option through the get method, deserialization will occur, which will allow arbitrary code execution This issue has been patched in version 1.8.178.
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.