Return-oriented programming

Return-oriented programming (ROP) is a computer security exploit technique that allows an attacker to execute code despite the presence of security defenses that would otherwise prevent it, such as executable-space protection and code signing. In this technique, an attacker gains control of the call stack to hijack program control flow and then executes carefully chosen machine instruction sequences that are already present in the machine's memory, called "gadgets".

Source: Wikipedia — Return-oriented programming (CC BY-SA 4.0)