A vulnerability in DBHub prior to version 0.22.6 allows bypassing read-only SQL validation on the MySQL and MariaDB connectors. This occurs due to incorrect parsing of double-dash comments in SQL statements, enabling an attacker to hide write or destructive commands from validation. The issue does not affect PostgreSQL. The vulnerability is fixed in version 0.22.6.
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 (`dblink` + `COPY ... TO PROGRAM`). The HTTP transport is unauthenticated and binds to `0.0.0.0` by default, so this is reachable by any network caller of `/mcp`. Version 0.22.6 patches the issue.
DBHub is a database MCP server for Postgres, MySQL, SQL Server, Oracle, MariaDB, SQLite. Versions prior to 0.22.5 expose an unauthenticated HTTP MCP endpoint when started with the documented HTTP transport mode, for example `--transport http --port 8080`. The HTTP server attempts to protect browser-origin access by checking whether the `Origin` hostname equals the `Host` hostname, then reflecting the validated `Origin` into `Access-Control-Allow-Origin`. This does not stop DNS rebinding. After an attacker-controlled hostname rebinds to a victim-accessible DBHub HTTP server, both `Origin` and `Host` can contain the attacker-controlled hostname, so DBHub accepts the request and dispatches MCP tool calls. As a result, a malicious website can deterministically invoke DBHub MCP tools from the victim's browser without prompt injection or model involvement. With the default demo configuration this can read and write the demo SQLite database; with a real configured database, the same primitive can read, enumerate, and potentially write database contents depending on DBHub's configured tool permissions and database credentials. Version 0.22.5 fixes the issue.