0-day(redirected from 0 day)
Used to describe a software security vulnerability that has just been exploited or discovered, often before the software developers can formally announce or create a fix (thus giving them "zero days" to preemptively address the issue). It was a 0-day attack—the developers had no idea that their program could be hacked in that way.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.