DBHub is a database MCP server for Postgres, MySQL, SQL Server, Oracle, MariaDB, SQLite. Prior to version 0.22.6, setting readonly = true on the execute_sql tool does not make the connection read-only. The connectors are written to set PostgreSQL default_transaction_read_only=on (and open SQLite in readOnly mode), but that code is gated on a config value that is never populated, so it never runs. The only thing left enforcing read-only is a classifier that inspects the first keyword of each statement. Any SELECT that writes or has side effects through a function call passes it. With an ordinary role this allows sequence tampering; with a privileged role it allows writing arbitrary files on the server (lo_export), reading arbitrary host files (pg_read_file), and remote code execution…