Common Vulnerabilities and Exposures (CVE) IDs are a unique identifiers given to security flaws. The CVE FAQ describes it best. CVE has be come a de facto standard for identifying vulnerabilities and security flaws.

A1. What is CVE?

CVE is a list of information security vulnerabilities and exposures that aims to provide common names for publicly known problems. The goal of CVE is to make it easier to share data across separate   
vulnerability capabilities (tools, repositories, and services) with this "common enumeration."

CVE monitors common vulnerability disclosure sources and assigns CVEs as new vulnerabilities are reported. To obtain a CVE before public disclosure, contact CVE or another CVE Numbering Authority (CNA).

See also:

A13. I discovered a new vulnerability or exposure. How can I obtain a CVE number?