Zero day
Also called: zero-day vulnerability
Course: AP® Cybersecurity Shows up in: Unit 1: Introduction to Security
An undocumented vulnerability that defenders do not know about yet, discovered and used by high-skilled adversaries.
Appears in the course and exam description (CED): 1.3.A.1
Why it matters in Unit 1
There is no patch for a zero day yet, so layered defenses matter.
Example
A skilled group finds an unknown flaw in a popular browser and uses it before the maker learns of it.
Learn it properly, with a checkpoint 1.3 Best Practices for Public Networks