CVE-2026-34976: Dgraph Affected by Pre-Auth Database Overwrite + SSRF + File Read via restoreTenant Missing Authorization

Dgraph is an open source distributed GraphQL database. Prior to 25.3.1, the restoreTenant admin mutation is missing from the authorization middleware config (admin.go), making it completely unauthenticated. Unlike the similar restore mutation which requires Guardian-of-Galaxy authentication, restoreTenant executes with zero middleware. This mutation accepts attacker-controlled backup source URLs (including file:// for local filesystem access), S3/MinIO credentials, encryption key file paths, and Vault credential file paths. An unauthenticated attacker can overwrite the entire database, read server-side files, and perform SSRF. This vulnerability is fixed in 25.3.1.