MITRE CVE (https://www.cve.org/) — is a search engine, database and generally accepted classifier of vulnerabilities.
NIST NVD (https://nvd.nist.gov/vuln/search) — search the official American government vulnerability database.
GitHub Advisory Database (https://github.com/advisories) — a database of vulnerabilities that includes CVEs and security recommendations.
CVEDetails (https://www.cvedetails.com/), (https://www.cvedetails.com/) osv.dev (https://osv.dev/list), (https://osv.dev/list) VulDB (https://vuldb.com/), (https://vuldb.com/) maltiverse (https://maltiverse.com/search) — a number of other sources of data on vulnerabilities and indicators of compromise.
opencve.io (https://www.opencve.io/cve) (https://www.opencve.io/cve)— (https://www.opencve.io/cve) CVE search engine with built-in alerts new threats.
security.snyk.io (https://security.snyk.io/)и (https://security.snyk.io/) Mend Vulnerability Database (https://www.mend.io/vulnerability-database/), (https://www.mend.io/vulnerability-database/) Vulncode-DB (https://www.vulncode-db.com/) — open source vulnerability databases.