Insecure Deserialization Deserialization is the return of a packed object into a form the application can use. The problem arises when an application accepts an object from an untrusted source and handles it as though it were safe. At that point the attacker is not sending mere data but a specially prepared structure that can change the flow of execution.

SSRF SSRF is a vulnerability in which the attacker gets a web server to send a request to an address of the attacker's choosing. The distinction matters: the request is not sent by the user's browser but by the server. That opens the door to internal services which from the outside ought to remain invisible.