Identification Failures in Chi (Go)

Identification Failures in Chi with Go occur when route parameters or request identifiers are not validated before being used to look up resources. Chi is a lightweight HTTP router for Go that relies on pattern-based routing and explicit parameter extraction. If an application uses chi.URLParam to retrieve an identifier such as an ID or slug and then directly uses that value in a database query without validation, it can lead to Insecure Direct Object References (IDOR) or Broken Object Level Authorization (BOLA). These are common in REST APIs where endpoints expose records via sequential or predictable identifiers, and the application lacks proper ownership or access checks.

With Go, developers often define routes like /users/{userID}/profile and extract the parameter using chi.URLParam(r, "userID"). If the downstream logic does not confirm that the authenticated subject is authorized to view or modify the requested userID, an attacker can modify the parameter to access other users' data. Chi does not enforce authorization; it only matches routes and provides parameter extraction. Therefore, identification failures arise from missing authorization logic, not from Chi itself, but from how Go code integrates with it. The risk is especially pronounced when the identifier type is not validated (e.g., expecting an integer but receiving a string or negative value), which can lead to invalid queries, information leakage, or secondary injection issues.

Real-world examples include APIs that expose resources by numeric IDs without ensuring the requesting user owns that resource, or admin-only endpoints that do not verify role claims. Since Chi does not provide built-in authorization, developers must implement checks explicitly. Without these, the API surface remains vulnerable to unauthenticated or low-privilege actors who can iterate through identifiers and map sensitive data exposure. Proper identification in Chi requires validating format, type, existence, and authorization before any data access.

Remediation focuses on validating and authorizing identifiers extracted from Chi routes. Always parse and validate input types, enforce ownership or role checks, and avoid using raw parameters in queries. Below are concrete Go examples that demonstrate secure handling within a Chi router.

Validate parameter format and type

Ensure the parameter matches the expected format before using it. For numeric IDs, use explicit conversion and error handling.

import (
    "net/http"
    "strconv"

    "github.com/go-chi/chi/v5"
)

func getUserProfile(w http.ResponseWriter, r *http.Request) {
    idStr := chi.URLParam(r, "userID")
    userID, err := strconv.Atoi(idStr)
    if err != nil || userID <= 0 {
        http.Error(w, `{"error": "invalid user ID"}`, http.StatusBadRequest)
        return
    }
    // proceed with validated userID
}

Enforce ownership or authorization

After validating the ID, confirm that the requesting subject has permission to access the resource. This typically involves checking claims in the request context and querying a data store.

func getUserProfileSecure(w http.ResponseWriter, r *http.Request) {
    idStr := chi.URLParam(r, "userID")
    userID, err := strconv.Atoi(idStr)
    if err != nil || userID <= 0 {
        http.Error(w, `{"error": "invalid user ID"}`, http.StatusBadRequest)
        return
    }

    subjectID := r.Context().Value("userID").(int) // from auth middleware
    if subjectID != userID {
        http.Error(w, `{"error": "forbidden"}`, http.StatusForbidden)
        return
    }

    // fetch user data safely
    w.Header().Set("Content-Type", "application/json")
    w.Write([]byte(`{"id": "` + idStr + `", "name": "alice"}`))
}

Use parameterized queries to prevent injection

When interacting with a database, always use parameterized queries or an ORM that enforces safe bindings. Do not concatenate identifiers into SQL strings.

import "database/sql"

func getUserByID(db *sql.DB, w http.ResponseWriter, r *http.Request) {
    idStr := chi.URLParam(r, "userID")
    userID, err := strconv.Atoi(idStr)
    if err != nil || userID <= 0 {
        http.Error(w, `{"error": "invalid user ID"}`, http.StatusBadRequest)
        return
    }

    var name string
    err = db.QueryRow("SELECT name FROM users WHERE id = $1", userID).Scan(&name)
    if err != nil {
        http.Error(w, `{"error": "not found"}`, http.StatusNotFound)
        return
    }

    w.Header().Set("Content-Type", "application/json")
    w.Write([]byte(`{"id": "` + idStr + `", "name": "` + name + `"}`))
}

Apply route-level middleware for common validation

Chi supports middleware that can validate parameters for a group of routes, reducing repetitive checks.

func ValidateID(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        idStr := chi.URLParam(r, "userID")
        if _, err := strconv.Atoi(idStr); err != nil {
            http.Error(w, `{"error": "invalid ID"}`, http.StatusBadRequest)
            return
        }
        next.ServeHTTP(w, r)
    })
}

r := chi.NewRouter()
r.With(ValidateID).Get("/users/{userID}", getUserProfile)