Reference
https://en.wikipedia.org/wiki/Vulnerability_(computing)
In computer security, a vulnerability is a weakness which can be exploited by a threat actor,
such as an attacker, to cross privilege boundaries (i.e. perform
unauthorized actions) within a computer system. To exploit a
vulnerability, an attacker must have at least one applicable tool or
technique that can connect to a system weakness. In this frame,
vulnerabilities are also known as the attack surface.