GlobalInformation security communitytechnicalneutral
- A previously unknown software or hardware vulnerability for which no public patch or official mitigation exists.
GlobalInformation security communitytechnicalinformal
- An exploit or piece of code that takes advantage of a zero-day vulnerability, typically used by attackers before defenders are aware.
GlobalUnderground/black-market contextsinformalcolloquial
- An item (for example, an exploit, encryption key, or vulnerability) traded covertly because it is previously undisclosed and therefore valuable.
GlobalComputingtechnicalneutral
- Used attributively to indicate that software, data, or an attack involves a zero-day vulnerability (e.g., zero-day exploit, zero-day attack, zero-day dataset).