There is never perfection in this process. Attackers might be using an exploit to a vulnerability that is not known within the security community. They might have developed an exploit to this vulnerability referred to as a “zero-day” exploit. Once the vulnerability is known in the community, the process mentioned above starts. Therefore, defenders must keep in mind that an exploit might already exist when the vulnerability is widely socialized. Sometimes vulnerabilities might be known within a closed community (e.g., vendor still developing a fix) for weeks, months, or years before it is disclosed publicly. Defenders have to be aware that there might always be vulnerabilities they cannot remediate, and therefore need to use other controls to mitigate.