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Vibe Coding · Lesson

Finding Security Gaps

Audit for common vulnerabilities.

Finding Security Gaps is a free Vibe Coding lesson on CoddyKit — lesson 3 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 Defaults Are Insecure

Models learn from public code, and most public code prioritizes clarity over safety. The statistical average of that corpus is an app with weak auth and trusting input handling.

So the baseline of generated software is demonstration-grade security. It works, it ships, and it leaks.

Finding the gaps is a deliberate adversarial pass, not something the happy-path demo will ever reveal.

Injection: The Classic

The most common AI-introduced flaw is injection: SQL built by string concatenation, shell commands assembled from user input, templates that interpolate untrusted data.

The generated query looks normal until an attacker sends an apostrophe. Then the query becomes their query.

Hunt for any place where user input is glued into a command, query, or markup string.

Scan this codebase for injection risks: SQL or NoSQL queries built by string concatenation, shell commands assembled from input, and any HTML or template that interpolates untrusted data. For each, show the vulnerable line and rewrite it using parameterized queries or proper escaping.

Broken Authorization

Authentication asks who you are; authorization asks what you may do. Models routinely add login then forget to check ownership on each resource.

The result is the classic IDOR: change the id in the URL and read someone else's data. The endpoint authenticated you, but never verified the record was yours.

Check every data access for an ownership or role check, not just a logged-in check.

Review every endpoint that reads or writes a record by id. For each, confirm there is an authorization check that the current user actually owns or is permitted to access that specific record. List any endpoint that only checks authentication but not ownership.

Secrets in Source

Ask for a working integration and the model will happily paste an API key inline to make the demo run. That key then lives in your git history forever.

Secrets belong in environment variables or a vault, never in committed code, client bundles, or logs.

Sweep for anything that looks like a key, token, or password hardcoded in the tree.

Search the entire repository, including history if possible, for hardcoded secrets: API keys, tokens, passwords, connection strings, and private keys. List each location and the secret type, and tell me which must be rotated because they were already committed.

Trusting the Client

Generated frontends often enforce rules only in the browser: price calculated client-side, role checked in JavaScript, validation done in the form.

An attacker bypasses all of it by calling your API directly. Anything the client computes, the server must recompute and re-verify.

Treat every request as if it came from a hostile script, because it can.

Identify every business rule that is currently enforced only on the client: price or total calculations, role and permission checks, and input validation. For each, add equivalent server-side enforcement and assume the client cannot be trusted.

Weak Input Validation

Models validate the field you mentioned and ignore the rest. Length limits, type checks, allowlists, and format rules get skipped unless requested.

Unbounded input invites denial of service, oversized uploads, and malformed data corrupting downstream systems.

Validate at the trust boundary with explicit allowlists, not blocklists that attackers route around.

Add strict server-side validation to this endpoint using an allowlist approach: enforce types, length and size limits, allowed character sets, and required fields. Reject anything that does not match rather than trying to sanitize bad input into shape.

Verbose Error Leakage

Helpful for debugging, dangerous in production: stack traces, SQL errors, and internal paths returned to the caller hand attackers a map of your system.

Models default to verbose errors because they make the demo easier to fix. Production needs generic messages to users and full detail only in private logs.

Separate what the user sees from what you record.

Find every place where internal error details leak to the client: raw stack traces, database error messages, file paths, or framework debug pages. Replace them with a generic client message and ensure the full detail is logged server-side only.

Missing Rate Limits

Login endpoints, password resets, and expensive queries without rate limiting are open to brute force and abuse. The model rarely adds throttling unasked.

An unlimited login endpoint is a credential-stuffing target. An unlimited search can be a denial-of-service lever.

Identify sensitive and costly endpoints and cap how often they can be called.

List the endpoints that need rate limiting: authentication, password reset, account creation, and any expensive query or external call. Recommend a per-user and per-IP limit for each and show how to enforce it with our middleware.

Dependency Risk

AI may pull in an outdated, abandoned, or even hallucinated package. Typosquatted dependency names are a real supply-chain attack vector.

Every import the model suggests is a trust decision. Verify the package exists, is maintained, and has no known critical vulnerabilities.

Run an audit tool and read what it flags rather than auto-upgrading blindly.

Review the dependencies this code introduced. Confirm each package actually exists and is actively maintained, flag any with known critical vulnerabilities, and watch for typosquatted names that resemble popular packages. Recommend safer alternatives where needed.

Think Like an Attacker

The most powerful prompt reframes the model from builder to adversary. Ask it to attack the code it just wrote.

A threat-modeling pass enumerates how each feature could be abused: what an attacker wants, what they control, and which assumption breaks first.

Adversarial review finds the gaps that constructive review walks right past.

Act as a penetration tester targeting this feature. Build a threat model: what would an attacker want, what inputs do they control, and what is the most damaging realistic attack? Walk through the strongest exploit step by step and tell me the smallest fix that closes it.

Defense in Depth

No single control is enough. Validate input and use parameterized queries and check authorization and limit rates. If one layer fails, the next still holds.

Models tend to add one fix and declare victory. Real hardening layers controls so a single mistake is not catastrophic.

Security is a property of the whole system, reviewed as a whole.

Quick Check

Test your security review instincts.

Recap

AI defaults to insecure code: injection, broken authorization, secrets in source, client-side trust, weak validation, leaky errors, no rate limits, and risky dependencies.

Hunt them with an adversarial pass, threat-model each feature, and layer controls for defense in depth. Next, you will harden the reviewed app for production.

Frequently asked questions

Is the “Finding Security Gaps” lesson free?

Yes — the full text of “Finding Security Gaps” 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 “Finding Security Gaps”?

Audit for common vulnerabilities. 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 3 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Finding Security Gaps” 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.

All lessons in this course

  1. Why AI Code Needs Review
  2. Generating Tests by Prompt
  3. Finding Security Gaps
  4. Hardening for Production
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