The Exploit Prediction Scoring System is a machine-learning model, run by FIRST, that gives each published CVE a probability of being exploited in the wild within the next 30 days. Scores are refreshed daily from threat intelligence, exploit code and other signals.
It answers a different question from CVSS. CVSS says how bad a flaw would be if used; EPSS says how likely it is to be used soon. Combining the two lets a team skip the many severe flaws that attackers ignore and focus on the smaller set they are working on.
EPSS only covers flaws with a CVE. Many AI agent findings, such as a prompt injection path through one agent’s email connector, are properties of a deployment and never get one, so they need a separate judgement of exploitability from red team and testing results.