Information Disclosure in Buffalo with Cockroachdb

Information disclosure occurs when an application unintentionally exposes data to parties that should not have access. The combination of Buffalo, a Go web framework, and CockroachDB, a distributed SQL database, can create exposure paths when developers inadvertently bypass authorization or leak sensitive data through error messages, logs, or misconfigured handlers.

Buffalo applications typically interact with databases via models and the pop ORM. If route handlers query CockroachDB without enforcing proper access controls, they may return records that the authenticated user is not permitted to view. For example, a handler that uses a simple Find without scoping by the current user ID can expose other users’ records, effectively performing an Insecure Direct Object Reference (IDOR) — a common cause of information disclosure.

CockroachDB’s wire protocol and default configurations do not inherently prevent this; the risk lies in how Buffalo routes and queries are written. When debugging is enabled in development mode, Buffalo may render detailed error pages that include SQL queries, table structures, and stack traces. If these pages are reachable from external networks, an attacker can learn schema details or valid column names, aiding further attacks.

Additionally, if the application serializes database models to JSON without filtering sensitive fields (such as password hashes, API keys, or internal flags), those fields can be transmitted to the client. Because Buffalo encourages rapid prototyping, it is easy to expose entire structs via render.JSON without whitelisting fields. An example is returning a User struct that includes PasswordDigest or ResetToken, which should never leave the server.

Logging practices compound the issue. If Buffalo logs full request parameters, headers, or response bodies to stdout or a file, and those logs are accessible to unauthorized personnel, sensitive data such as tokens or personal identifiers can be exposed. When using CockroachDB, query logs may also capture bound parameters, revealing PII if structured logging is not carefully controlled.

To illustrate, consider a Buffalo handler that retrieves a user profile:

// handlers/user.go
func Show(c buffalo.Context) error {
    userID := c.Param("user_id")
    u := &models.User{}
    if err := models.DB.Find(u, userID); err != nil {
        return c.Error(500, errors.New("user not found"))
    }
    return c.Render(200, r.JSON(u))
}

This snippet does not scope the query to the requesting user and returns the entire struct. If User contains sensitive fields, they are disclosed. Moreover, the error message reveals that the lookup used a direct ID, which can be probed for existence of other IDs (IDOR).

Remediation focuses on scoping queries, filtering output, and hardening error handling. Always scope database queries by the current user’s identifier and avoid returning raw models to the client.

First, ensure that every query that accesses user-specific data includes a tenant or user scope. For example, instead of looking up by ID alone, combine the ID with the current user’s ID:

// handlers/user.go
func Show(c buffalo.Context) error {
    userID := c.Param("user_id")
    currentUser := c.Value("current_user").(*models.User)
    u := &models.User{}
    // Scope by current user to prevent IDOR
    if err := models.DB.Where("id = ? AND team_id = ?", userID, currentUser.TeamID).First(u); err != nil {
        return c.Error(404, errors.New("not found"))
    }
    // Explicitly select safe fields
    safeUser := struct {
        ID   uuid.UUID `json:"id"`
        Name string    `json:"name"`
        Role string    `json:"role"`
    }{ID: u.ID, Name: u.Name, Role: u.Role}
    return c.Render(200, s.JSON(safeUser))
}

This ensures that even if an attacker manipulates user_id, they cannot access records outside their team. Using First with a composite condition enforces row-level security at the query level.

Second, disable debug pages in production and standardize error responses. In env.yml, set buffalo_env to production and ensure dev_mode is false. In your app’s actions initialization, avoid exposing internal errors:

// actions/app.go
if appEnv == buffalo.EnvProduction {
    app.Use(middleware.NullRenderer{Nil{"error": "Internal server error"}})
}

Third, filter sensitive fields before serialization. Define explicit structs or use projection queries to return only necessary data. For CockroachDB, you can also use row-level security (RLS) if the database supports it in your deployment, but the application layer must still enforce checks.

Finally, audit logs to ensure they do not contain sensitive payloads. Configure log formatting to exclude request bodies or mask sensitive fields. These steps reduce the likelihood of information disclosure when using Buffalo with CockroachDB.