Image Credit: Zero-Day Vulnerability Explained
In summary, a vulnerability is some type of system flaw. They appear in all
levels of computing, from surface level software, to operating systems, to firmware.
The most infamous pieces of malware exploit one or more vulnerabilities to maximize damage.
The "freshest" vulnerabilities are known as zero-days.
When new vulnerabilties are discovered, they are added to the National Vulnerability Database (NVD).
This database is maintained by the National Institute of Standards and Technology, U.S. Department of Commerce.
Using the power of Web APIs, you can look up information about a vulnerability in this database with just its CVE number!
Example: WannaCry exploited the EternalBlue vulnerability, which is stored as CVE-2017-0144