What is a zero-day exploit?

A zero-day exploit refers to a security vulnerability that is unknown to the software vendor. This type of vulnerability is particularly dangerous because it can be exploited by attackers before the vendor has had the opportunity to create and distribute a fix or patch. As a result, there is a "zero-day" window during which the vulnerability is active and can be targeted, placing systems at significant risk.

Understanding this concept is crucial in cybersecurity, as the lack of awareness on the part of the vendor means that there are no defenses in place to protect against the exploit, making it highly valuable to malicious actors. As soon as a zero-day vulnerability is discovered, it becomes critical for the software vendor to work quickly to find a solution and disseminate it to users, highlighting the ongoing battle between security researchers and cybercriminals.