Open Redirect in Gorilla Mux with Cockroachdb

An open redirect in a Gorilla Mux service that uses Cockroachdb as the backend can occur when route variables intended for database identity are repurposed for client-facing redirects without strict validation. For example, a handler might read a team_id URL parameter to select a Cockroachdb tenant or database row, then use that same value in a redirect response. Because Cockroachdb does not perform HTTP redirects, the risk is not in the database itself but in how the application uses data retrieved from it.

Consider a handler that fetches a tenant record by ID from Cockroachdb and then redirects to a supposed tenant dashboard. If the handler trusts the client-supplied redirect target or constructs a location header using unchecked inputs, an attacker can supply a malicious URL. The handler might still query Cockroachdb safely using parameterized statements, but the redirect logic operates on unchecked strings, bypassing the safety of the database layer.

Gorilla Mux routes like /tenant/{team_id}/login can encourage this pattern: the path parameter identifies a Cockroachdb row, but if the application then uses a second parameter such as next to decide where to send the user, and does not validate or restrict next, an open redirect is possible. The presence of Cockroachdb can create a false sense of safety if developers assume that database interactions automatically sanitize downstream outputs.

Real-world attack patterns include phishing pages that embed a legitimate domain, then abuse the redirect to steer users to credential-harvesting sites. While this is not a vulnerability in Cockroachdb, it is a risk introduced when application code combines database-driven decisions with unvalidated redirect targets. The OWASP API Top 10 categorizes this as a broken access control and improper redirect issue, and it can undermine authentication flows and tenant isolation assumptions even when backend data stores are correctly configured.

Remediation focuses on strict validation and canonicalization of any values used to construct HTTP redirects, independent of how data is stored in Cockroachdb. Even if you use secure Cockroachdb queries, you must treat redirect targets as untrusted input.

Example: Safe handler with Cockroachdb and validated redirects

//go
package main

import (
	"context"
	"net/http"
	"strings"

	"github.com/gorilla/mux"
	"github.com/jackc/pgx/v5/pgxpool"
)

func tenantHandler(pool *pgxpool.Pool) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		vars := mux.Vars(r)
		teamID := vars["team_id"]

		// Validate teamID format before using it.
		if !isValidTeamID(teamID) {
			http.Error(w, "invalid team identifier", http.StatusBadRequest)
			return
		}

		// Safe Cockroachdb query using parameterized statements.
		var tenantName string
		row := pool.QueryRow(r.Context(), "SELECT name FROM tenants WHERE id = $1", teamID)
		if err := row.Scan(&tenantName); err != nil {
			http.Error(w, "tenant not found", http.StatusNotFound)
			return
		}

		// Only allow redirects to paths within this service.
		allowedHost := "https://api.example.com"
		target := strings.TrimSuffix(allowedHost, "/") + "/dashboard/" + tenantName

		http.Redirect(w, r, target, http.StatusSeeOther)
	}
}

func isValidTeamID(id string) bool {
	// Allow only alphanumeric and underscores.
	for _, r := range id {
		if !(r == '_' || (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9')) {
			return false
		}
	}
	return id != "" && len(id) <= 64
}

In this example, the Cockroachdb query is safe and uses placeholders, but the redirect target is constructed only from server-controlled values (tenant name derived from the verified ID). The next parameter is not used, eliminating the open redirect risk.

Rejecting untrusted redirect targets

//go
// Reject any user-controlled redirect targets.
func safeRedirect(w http.ResponseWriter, r *http.Request, target string) {
	// Do not allow redirects to external hosts or paths provided by the client.
	const allowedHost = "https://api.example.com"
	if !strings.HasPrefix(target, allowedHost) {
		http.Error(w, "redirect not allowed", http.StatusBadRequest)
		return
	}
	// Additional canonicalization can be applied here.
	http.Redirect(w, r, target, http.StatusSeeOther)
}

By enforcing a strict allowlist approach and avoiding dynamic redirect construction from any client-influenced data, you prevent open redirect abuse while still interacting safely with Cockroachdb. MiddleBrick scans can help detect endpoints where redirect logic depends on unchecked inputs, even when database queries themselves are correct.