Patch Tuesday is the unofficial name of Microsoft’s scheduled release of the newest security fixes for its Windows operating system and other software applications, as documented in the Windows Security Updates Guide. Patch Tuesday occurs on the second Tuesday of every month.

This article will offer a quick guide to vulnerabilities – what they are, how they can be exploited and the consequences of exploitation. A vulnerability is a weakness in an asset that can be exploited by cyber attackers. It’s a known issue that allows an attack to succeed. 

A zero-day is a weakness in hardware, software or firmware that is not known to the parties responsible for patching or fixing the flaw. The term zero refers to an attack that has zero days between the time the vulnerability is discovered and the first attack. Once a zero-day vulnerability is known to the public, it’s known as a one-day or n-day vulnerability.

What is a zero-day vulnerability?

A zero-day (or 0-day) vulnerability is a software vulnerability that hasn’t been publicly disclosed or was recently discovered due to a successful attack. Once the threat is discovered, the race is on to patch the vulnerability before it can be exploited. In other words, the software developers have zero days to fix the vulnerability.