What does the term 'zero-day vulnerability' mean?

The term 'zero-day vulnerability' refers to a flaw that is unknown to the vendor or the software development team, meaning that there is no available patch or fix at the time it is discovered. Because the vendor is unaware of the vulnerability, it is particularly dangerous; attackers can exploit it to gain unauthorized access to systems or data before the vendor has the opportunity to address the issue.

This concept is critical in cybersecurity because once a vulnerability is known, it typically becomes a race between the vendor issuing a patch and attackers attempting to exploit the vulnerability. The term "zero-day" highlights the idea that the software developers have had zero days to address the vulnerability since they are unaware of its existence. Understanding this dynamic is key for cybersecurity professionals as they work to protect systems from such vulnerabilities.