A vulnerability is a weakness in a computer system or software which can be exploited to perform unauthorized access of a system, network, website or device. The good guys, i.e., white hat security researchers discover a vulnerability, they report the issue immediately to the software vendors. On the other hand, when its the bad guy, the hacker, who discovers the vulnerability, it can be used to carry out malicious activities like data breaches and network hijacking.”]
Source: https://hackercombat.com/knowledge-base/a-beginners-guide-to-vulnerabilities/