Security Flaw: Hardcoded JWT Secrets in Backend Code Risk Full Authentication Compromise

A critical security vulnerability has been identified in a backend application's configuration, where hardcoded, easily guessable default values for JWT secrets create a severe exposure risk. The flaw, located in the `backend/src/config/index.js` file, allows the system to fall back to these insecure defaults if the proper environment variables are not set. This insecure default configuration could enable an attacker to forge administrative tokens and completely compromise the entire authentication system.

The vulnerability centers on two specific lines of code that define the `jwtSecret` and `jwtRefreshSecret`. The configuration uses a logical OR operator to default to strings like 'your-secret-key-change-in-production' if the `JWT_SECRET` or `JWT_REFRESH_SECRET` environment variables are undefined. This creates a high-risk scenario, particularly in a production deployment where these variables might be inadvertently missed, leaving the system protected by a publicly known secret.

This exposure represents a fundamental failure in secure-by-design principles. The recommended remediation is to remove these default fallback values entirely. The application should be modified to throw a fatal error and refuse to start if these critical security environment variables are not provided, forcing explicit configuration and eliminating the risk of accidental deployment with compromised secrets. The flaw underscores the persistent danger of insecure defaults in authentication systems.