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What are some common security vulnerabilities in full-stack applications and how do you prevent them?

Security is critical in full-stack development because you’re responsible for both front-end and back-end integrity. Here’s a breakdown of the most common vulnerabilities across the stack and how to prevent them:

What are some common security vulnerabilities in full-stack applications and how do you prevent them?

🔒 Common Full-Stack Security Vulnerabilities & Prevention

1. SQL Injection (Backend)

What it is: Malicious SQL queries injected into inputs (e.g., login forms).
Risk: Data leaks, unauthorized access, even DB destruction.

Prevention:

  • Use parameterized queries or ORMs (e.g., Sequelize, Prisma, Hibernate)

  • Never concatenate strings to form SQL

  • Input validation and sanitization

2. Cross-Site Scripting (XSS) (Frontend)

What it is: Injecting malicious scripts into websites that execute in users’ browsers.
Risk: Session hijacking, phishing, data theft.

Prevention:

  • Escape or sanitize all user-generated content before rendering

  • Use Content Security Policy (CSP) headers

  • Frontend frameworks (e.g., React, Vue) help mitigate this automatically

3. Cross-Site Request Forgery (CSRF)

What it is: Unauthorized commands sent from a trusted user's browser.
Risk: Account changes, payments, etc., without user consent.

Prevention:

  • Use CSRF tokens for state-changing requests

  • Enable SameSite cookies

  • Use secure HTTP-only cookies

4. Insecure Authentication

What it is: Weak login flows, poor password handling.
Risk: Account takeovers, brute-force attacks.

Prevention:

  • Use hashed passwords with bcrypt/scrypt/Argon2

  • Implement rate limiting and account lockouts

  • Use JWT or OAuth securely for session management

  • Enable MFA (Multi-Factor Authentication)

5. Broken Access Control

What it is: Users access resources they shouldn’t (e.g., admin functions).
Risk: Data exposure, privilege escalation.

Prevention:

  • Enforce backend access controls (don’t rely on frontend alone!)

  • Implement role-based access control (RBAC)

  • Validate user identity and permissions on every protected route

6. Sensitive Data Exposure

What it is: Transmitting or storing data without encryption.
Risk: Leaks of PII, payment info, etc.

Prevention:

  • Use HTTPS everywhere (TLS)

  • Encrypt data at rest and in transit

  • Avoid logging sensitive info (passwords, tokens, etc.)

7. Security Misconfiguration

What it is: Unsecured headers, debug info in prod, unnecessary services open.
Risk: Varies—can expose whole system.

Prevention:

  • Disable debug/error messages in production

  • Configure proper HTTP headers (CORS, CSP, HSTS, X-Frame-Options)

  • Remove unused services, APIs, routes

8. Third-Party Vulnerabilities

What it is: Insecure libraries, plugins, or dependencies.
Risk: One bad dependency = full compromise.

Prevention:

  • Use npm audit, Snyk, or OWASP Dependency-Check

  • Keep packages up to date

  • Pin dependency versions and use a lock file

9. API Abuse

What it is: Excessive requests, unauthorized API usage.
Risk: Data scraping, DoS, rate-based attacks.

Prevention:

  • Rate limiting (e.g., Express Rate Limit, API Gateway policies)

  • Authentication + API keys

  • Use GraphQL complexity limits or REST pagination

10. Improper Logging and Monitoring

What it is: Lack of insight into attacks or system anomalies.
Risk: Breaches go undetected.

Prevention:

  • Log suspicious activity (login failures, access violations)

  • Use tools like Sentry, Datadog, ELK stack

  • Set up alerts for anomalies or threshold events

🔐 Bonus Tip: OWASP Top 10

Regularly review the OWASP Top 10 for updated risks and best practices—it's like a cheat sheet for staying secure.

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