Computer Vulnerability

In its broadest sense, the term 'vulnerability' is associated with some violation of a security policy. This may be due to weak security rules, or it may be that there is a problem within the software itself. In theory, all computer systems have vulnerabilities; whether or not they are serious depends on whether or not they are used to cause damage to the system.
When trying to gain unauthorized access to a system, an intruder usually first conducts a routine scan (or investigation) of the target, collects any 'exposed' data, and then exploits security policy weaknesses or vulnerabilities. Vulnerabilities and exposures are therefore both important points to check when securing a system against unauthorized access.