I built a security scanner for AI-generated code — here's what it found

Vibe coding is everywhere. You prompt Claude or ChatGPT, paste the output, ship it. Fast. But here's the problem nobody talks about: AI models consistently produce the same security mistakes, over and over.

I spent the last few months building a scanner specifically for this pattern. Here's what I found.

The Problem With AI-Generated Code

When an LLM writes code, it optimizes for working code, not secure code. And it tends to make the same class of mistakes:

# AI loves this pattern — looks clean, is dangerous

def get_user(user_id):

    query = f"SELECT * FROM users WHERE id = {user_id}"  # SQL injection

    return db.execute(query)

# AI generates this constantly for file handling

def read_file(filename):

    path = os.path.join(BASE_DIR, filename)  # path traversal if filename = "../../etc/passwd"

    return open(path).read()

# The "vibe coding" stub — looks implemented, does nothing

def save_user_data(data):

    # TODO: implement database saving

    return {"status": "saved"}  # MISSING_WRITE: no actual DB write

These aren't obscure edge cases. They're patterns that appear in AI-generated code constantly because the models learned from code that had these issues.

What I Built: VibeGuard

VibeGuard is an AST-based scanner with 48 detection patterns specifically tuned for AI-generated code:

• 
  33 security patterns: SQL injection, command injection, path traversal, XSS, SSRF, hardcoded secrets, eval/exec, weak crypto...


• 
  15 vibe-coding patterns: stub skeletons, missing DB writes, fake async, dead call results, hardcoded lookup tables...


• 
  9 languages: Python, JavaScript, TypeScript, Go, Ruby, Java, PHP, Kotlin, C/C++

The key difference from tools like Bandit or Semgrep: VibeGuard knows what AI-generated code looks like. It doesn't just find security bugs — it finds the specific anti-patterns that emerge when LLMs write code.

Try It Right Now (30 seconds)

No install needed. Just curl:

curl -X POST https://pleasing-transformation-production-90c2.up.railway.app/v1/scan \

  -H "X-API-Key: vg_free_test" \

  -F "file=@your_file.py"

Response:

{

  "filename": "app.py",

  "blocks": 2,

  "warns": 5,

  "issues": [

    {

      "kind": "SQL_INJECTION_RISK",

      "severity": "BLOCK",

      "line": 23,

      "detail": "f-string interpolation in SQL — use parameterized queries"

    }

  ]

}

Python:

import requests



with open("app.py", "rb") as f:

    r = requests.post(

        "https://pleasing-transformation-production-90c2.up.railway.app/v1/scan",

        headers={"X-API-Key": "vg_free_test"},

        files={"file": f}

    )

print(r.json())

Add It to GitHub CI (2 minutes)

# .github/workflows/vibeguard.yml

name: VibeGuard Security Scan

on: [pull_request]

jobs:

  scan:

    runs-on: ubuntu-latest

    steps:

      - uses: actions/checkout@v4

      - uses: Moonsehwan/aina-vibeguard-action@v1

        with:

          api-key: ${{ secrets.VIBEGUARD_KEY }}

          fail-on-block: 'true'

Every PR gets scanned. AI-generated SQL injection or stub skeleton → merge blocked.

The 15 Vibe-Coding Patterns

This is what makes VibeGuard different. These patterns don't exist in traditional scanners:

If you've used Claude Code, Cursor, or Copilot heavily, I promise you have at least one of these.

Real Finding

I scanned a popular open-source AI coding assistant (25K+ stars):

BLOCK  COMMAND_INJECTION  agent.py:1222

       subprocess.Popen(cmd, shell=True)

       any malicious config file can execute arbitrary commands

Found in 3 seconds. Bandit missed it. Semgrep missed it.

vs Bandit / Semgrep

The gap is the AI-specific patterns. Bandit and Semgrep are great — they just weren't designed for LLM-generated code.

Try It

• 
  Free API key: vg_free_test (50 files/day, Pro features free until June 24)


• 
  GitHub:
  

Scan your AI-generated code before it ships. 30 seconds, you'll be surprised what you find.

AST-based, deterministic. Same input always gives same output. No LLM in the scan pipeline.