Zero-day

Back then, having "zero day warez" (brand new cracked games that are not even one day old yet) on your BBS first was a big status symbol.

Source: wiktionary

If your software is popular and has a high demand, you will want to defend against the "zero-day" cracker.

Source: wiktionary

Before discussing ways to counter zero-day attacks, let's begin with the definition of what a zero-day attack is. A zero-day attack is one that the vendor does not yet know about or hasn't been fixed.

Source: wiktionary

2005, Valdes et al, Recent Advances in Intrusion Detection Automatically creating reliable signatures of zero-day exploits is the focus of intense research efforts.

Source: wiktionary