10 Common WebApp Vulnerabilities and How to Harden Against Them

Why Security Must Be Built In, Not Bolted On

Security vulnerabilities in web applications cost businesses billions of dollars annually. The OWASP Top 10 represents the most critical security risks, and understanding them is essential for every developer.

1. Broken Access Control

This is now the #1 vulnerability. Always validate permissions server-side, never trust client-side restrictions.

// Laravel: Always use policies\n$this->authorize('update', $post);\n

2. SQL Injection

Use parameterised queries exclusively. Never interpolate user input into SQL strings.

// WRONG:\nDB::select("SELECT * FROM users WHERE id = {$id}");\n// CORRECT:\nDB::select("SELECT * FROM users WHERE id = ?", [$id]);\n

3. Cross-Site Scripting (XSS)

Always escape output. In Blade: use {{ }} not {!! !!} unless you explicitly trust the source.

Security Headers Checklist

• Content-Security-Policy (CSP)
• X-Frame-Options: DENY
• X-Content-Type-Options: nosniff
• Strict-Transport-Security (HSTS)
• Referrer-Policy: strict-origin-when-cross-origin