Zero Day Attack
A zero day attack is a cyberattack which exploits a potentially serious security weakness that is unknown to software developers, meaning they have had no chance to fix it.
Zero-Day Threat
A zero-day threat (also known as a zero-day exploit) is an attempt by a threat actor to take advantage of a security vulnerability that doesn't have a fix in place. It is called a zero-day threat as once the vulnerability has been discovered; developers have "zero days" to create a fix for it. [...]