Risks database

Before calculate risks, you need to identify threats and vulnerabilities, and I am not sure if there are a public risks database, but you can find public catalogues of threats and vulnerabilities. For example, you can find a catalogue in the ISO 27005. And also you can find a public catalogue here "Catalogue of threats & vulnerabilities" : https://advisera.com/27001academy/knowledgebase/threats-vulnerabilities/
By the way, each country also has Computer Emergency Readiness Teams (CERT) which, among other things, distributes information about vulnerabilities and threats. One example can be the United States Computer Emergency Readiness Team (US-CERT): https://www.us-cert.gov