What is a 'Zero Day' vulnerability?

A 'Zero Day' vulnerability refers to a security flaw that is unknown to the software vendor or developer. This means that there has been no patch or fix created for this vulnerability because the vendor is not aware of its existence. Consequently, it is termed "zero day" because it has been uncovered and there are zero days available to address it before it can potentially be exploited by attackers.

This type of vulnerability is particularly dangerous; once it is discovered, attackers can exploit it before the vendor has a chance to issue a fix. This situation underscores the importance of strong security measures and prompt vulnerability management processes to mitigate risks associated with such unforeseen vulnerabilities. The understanding of Zero Day vulnerabilities is crucial for cybersecurity professionals as it emphasizes the need for proactive security strategies rather than just reactive responses following the disclosure of known vulnerabilities.