CVSS (vulnerability severity score)

CVSS is a standard score that describes the severity of a flaw on a scale from 0 to 10, taking into account, among other things, how easy it is to exploit and how much damage it can cause. The higher the score, the more urgent the response.

By convention: 9.0-10 is critical, 7.0-8.9 high, 4.0-6.9 medium. Critical flaws, especially ones exploitable without logging in, require an immediate update.