You are a maintainer of a repository and Dependabot notifies you of a vulnerability.

Comprehensive and Detailed Explanation:

Dependabot alerts are generated based on data from various sources:​

National Vulnerability Database (NVD): A comprehensive repository of known vulnerabilities, which GitHub integrates into its advisory database.​

GitHub Docs

Security Advisories Reported on GitHub: GitHub allows maintainers and security researchers to report and discuss vulnerabilities, which are then included in the advisory database.​

The dependency graph and manifest/lock files are tools used by GitHub to determine which dependencies are present in a repository but are not sources of vulnerability disclosures themselves.​