Vibe Coding · Lesson

Security Basics for AI Code

Avoid the risks AI often misses.

Security Basics for AI Code is a free Vibe Coding lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Vibe Coding learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

AI Writes Fast — Sometimes Unsafely

AI is brilliant at getting something working quickly. But "working" and "safe" aren't the same. AI often leaves real apps open to attacks because it optimizes for the happy path, not for hostile users.

The good news: a handful of habits catch most problems, and you can ask AI to apply them. This lesson covers the security risks vibe coders hit most.

Never Put Secrets in Code

The #1 mistake: pasting an API key or password directly into your code. If that code goes to GitHub, the key is public forever — bots scan for leaked keys within minutes.

Secrets belong in environment variables, never in the source. Spot the difference below.

// DANGER: key is hardcoded and will leak
const apiKey = 'sk-live-abc123realkey';

// SAFE: key comes from the environment, not the code
const apiKey = process.env.API_KEY;

if (!apiKey) {
  throw new Error('API_KEY is missing — set it in your .env file');
}

Keep Secrets Out of Git

Store secrets in a .env file, and make sure Git ignores that file so it never gets committed. One line in .gitignore does it.

Ask your AI tool to set this up correctly from the start.

Set up environment variables for this project:
- create a .env file with API_KEY=
- add .env to .gitignore so it's never committed
- create a .env.example with empty placeholders to commit instead
- show me where the code reads process.env.API_KEY

Never Trust User Input

The golden rule of security: anything a user can type, a user can lie about. Attackers send broken, oversized, or malicious input on purpose. Your code must validate it.

Here's a basic guard that checks input before using it.

function createUser(input) {
  if (typeof input.email !== 'string' || !input.email.includes('@')) {
    return { error: 'Invalid email' };
  }
  if (input.age < 0 || input.age > 150) {
    return { error: 'Invalid age' };
  }
  return { ok: true };
}

console.log(createUser({ email: 'bad', age: 30 }));
console.log(createUser({ email: 'a@b.com', age: 30 }));

SQL Injection: A Classic AI Slip

If AI builds your database query by gluing user input into a string, an attacker can inject their own commands and steal or delete data. This is SQL injection.

The fix is parameterized queries — the database treats input as data, never as commands. Always ask AI to use them.

// DANGER: user input glued straight into the query
db.query("SELECT * FROM users WHERE email = '" + email + "'");

// SAFE: parameterized — the ? is filled in safely
db.query('SELECT * FROM users WHERE email = ?', [email]);

Ask AI to Review for Security

You can turn the AI into a security reviewer. Paste your code and ask it to hunt for vulnerabilities specifically — it's much better at finding them when you ask directly.

Review this code for security problems. Specifically check for:
- hardcoded secrets or API keys
- unvalidated user input
- SQL injection
- missing authentication checks
List each issue, why it's risky, and the fix. Here is the code: <paste>

Protect What Should Be Private

AI often builds an endpoint that returns data without checking who is asking. That means anyone could read another user's data just by changing an ID in the URL.

Every sensitive action needs an authorization check: is this user allowed to do this?

// DANGER: anyone can read any order by guessing the id
app.get('/orders/:id', (req, res) => {
  res.json(getOrder(req.params.id));
});

// SAFE: only the owner can see their order
app.get('/orders/:id', (req, res) => {
  const order = getOrder(req.params.id);
  if (order.userId !== req.user.id) return res.status(403).end();
  res.json(order);
});

Keep Dependencies Updated

Your app uses many packages written by others. Some have known security holes. Outdated dependencies are one of the most common ways apps get hacked.

A quick command checks for known vulnerabilities, and AI can help you understand the results.

# Check installed packages for known vulnerabilities
npm audit

# Then ask AI:
# "npm audit reports 3 high-severity issues in <package>.
#  Explain the risk in plain English and tell me the safest way to fix it."

Don't Leak Errors to Users

When something breaks, AI-generated code sometimes shows the raw error — including file paths, database details, or stack traces. That's a gift to attackers.

Log details privately on the server, but show users a generic, friendly message.

try {
  doRiskyThing();
} catch (err) {
  console.error('Internal error:', err); // private log
  res.status(500).json({ error: 'Something went wrong. Please try again.' });
  // never send err.stack or err.message to the user
}

A Security Checklist You Can Reuse

Before you ship anything, run through this. Paste it to your AI and ask it to verify each item against your code.

No secrets in the code or Git history.
All user input validated.
Database queries are parameterized.
Sensitive routes check who is logged in and what they're allowed to do.
Dependencies audited and updated.
Errors logged privately, generic messages to users.

Security Is a Conversation, Not a One-Time Step

You won't catch everything, and that's fine. The mindset that protects you: assume AI code is insecure until reviewed, ask security questions every time you add a feature, and re-run your checklist before each deploy.

Treat the AI as a careful partner you actively interrogate — not an oracle you blindly trust.

Quick Check

Your AI assistant generates a login feature and hardcodes the database password right in the source file. What should you do?

Recap: Safe by Habit

AI ships fast but skips safety, so you supply the safety. You learned to: keep secrets out of code, validate all input, use parameterized queries, add authorization checks, audit dependencies, and hide raw errors.

Best of all, you can ask AI to review for these exact issues and run a checklist before every deploy. Next: keeping your code clean and maintainable.

Frequently asked questions

Is the “Security Basics for AI Code” lesson free?

Yes — the full text of “Security Basics for AI Code” is free to read here on the web, and the Vibe Coding course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Vibe Coding course, upgrade to CoddyKit PRO.

What will I learn in “Security Basics for AI Code”?

Avoid the risks AI often misses. You practise Vibe Coding with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Vibe Coding?

No prior experience is required. Vibe Coding on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Security Basics for AI Code” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Vibe Coding lesson?

Yes. Every Vibe Coding lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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