Api Key Exposure in Chi with Mysql

Chi is a server-side rendering (SSR) framework for the Deno runtime, and it often interacts with backend data sources such as MySQL. When API keys are embedded in Chi server-side code or in client-rendered templates that are served to the browser, they can be inadvertently exposed to authenticated or unauthenticated users depending on routing and template configuration. If a Chi application constructs dynamic SQL queries by interpolating request parameters directly into strings, an attacker may manipulate those parameters to trigger verbose error messages that reveal connection strings or keys. Additionally, if the application exposes administrative or debugging endpoints without proper access controls, keys stored in environment variables for MySQL connections can leak through logs, error traces, or misconfigured HTTP headers. MiddleBrick scans this attack surface by testing unauthenticated endpoints and analyzing OpenAPI specifications to detect whether API-related secrets are exposed through error responses or overly permissive routes.

MySQL-specific risks in Chi arise when connection credentials are hardcoded or improperly scoped. For example, storing a MySQL password in a Deno environment variable that is accessible from within a Chi route handler increases the chance of exposure if that handler is compromised through path traversal or insecure direct object references (IDOR). MiddleBrick’s BOLA/IDOR checks simulate unauthorized access to endpoints that should be restricted, verifying whether a Chi route leaking a MySQL connection string could be accessed without authentication. The scanner also tests for Input Validation weaknesses where malformed queries might cause the application to return stack traces containing sensitive configuration data, including API keys used to authenticate to downstream services.

Another vector involves the use of OpenAPI specs generated by Chi applications. If the spec unintentionally references internal endpoints or includes parameters that expose database credentials during introspection, MiddleBrick’s spec analysis cross-references runtime behavior with declared definitions to identify mismatches. This helps detect scenarios where an endpoint meant for internal use inadvertently reveals metadata about the MySQL integration, including user roles or key identifiers. LLM/AI Security checks further ensure that system prompts used within Chi-powered AI features do not contain embedded credentials or connection logic that could be extracted via prompt injection techniques, a unique capability when API logic is partially driven by language models.

To mitigate API key exposure in Chi applications using MySQL, implement strict separation between application logic and sensitive configuration. Store MySQL credentials in Deno environment variables that are injected at runtime rather than hardcoded in source files. Use Chi’s middleware to enforce authentication on routes that interact with the database, and ensure that error handling does not return raw query details to the client. The following code example demonstrates a secure pattern for connecting to MySQL within a Chi application without exposing credentials in logs or responses.

import { chi } from 'https://deno.land/x/[email protected]/mod.ts';
import { createPool, PoolClient } from 'https://deno.land/x/[email protected]/mod.ts';

const pool = createPool({
  hostname: Deno.env.get('DB_HOST') || 'localhost',
  port: 3306,
  user: Deno.env.get('DB_USER'),
  password: Deno.env.get('DB_PASSWORD'),
  db: Deno.env.get('DB_NAME'),
});

const app = chi();

app.get('/api/users/:id', async (ctx) => {
  const client: PoolClient = await pool.connect();
  try {
    const userId = ctx.params.id;
    // Use parameterized queries to prevent injection and avoid exposing internal errors
    const result = await client.query('SELECT id, name, email FROM users WHERE id = ?', [userId]);
    ctx.body = result[0];
  } catch (error) {
    // Generic error response to avoid leaking stack traces or keys
    ctx.status = 500;
    ctx.body = { error: 'Internal server error' };
  } finally {
    client.release();
  }
});

app.listen({ port: 8080 });

Complement code-level fixes with continuous scanning using the middlebrick CLI to detect exposed keys in runtime responses. Developers can integrate scans into local workflows or CI/CD pipelines using the GitHub Action to fail builds if a scan detects patterns resembling API keys in output. For teams managing many services, the Pro plan enables continuous monitoring and automated alerts when new exposure risks appear. The MCP Server allows AI coding assistants to trigger scans directly, helping developers identify insecure patterns during development rather than after deployment.

Regularly rotate MySQL credentials and audit access logs to detect unusual query behavior. Ensure that Chi routes returning database-related errors are configured to suppress detailed messages in production. By combining secure coding practices with automated scanning, teams reduce the likelihood of API keys being exposed through MySQL-related endpoints.