Common Security Mistakes Developers Still Make (and How to Avoid Them)
In an era where even small applications can handle thousands of user records, software security should be a baseline, not a bonus. And yet, development teams — even experienced ones — continue to make basic mistakes that expose users, companies, and infrastructure to unnecessary risk.
These aren’t exotic zero-day vulnerabilities. They’re simple, well-known issues that happen because security often takes a back seat to deadlines, product features, or developer convenience.
Let’s take a closer look at a few of the most common missteps — and how to prevent them before they ship.
1. Hardcoding Secrets and Credentials
It’s still surprisingly common to find API keys, database passwords, or admin tokens hardcoded in source files — or worse, pushed to public repositories.
Hardcoded secrets are dangerous because they create fixed, exposed access points. If a developer forgets to remove them before committing, they’re instantly vulnerable — and automated bots are constantly scanning GitHub for them.
Fix: Use environment variables, secrets managers (like Vault, AWS Secrets Manager), and automated scans to catch exposed credentials before deployment.
2. Poor Input Validation
Accepting unvalidated user input is one of the oldest security holes in the book — and it's still around. Whether it leads to SQL injection, XSS, or broken logic, unfiltered input is one of the easiest ways to compromise an app.
Many modern frameworks offer built-in protection, but relying on that alone is a mistake. Developers must understand what they’re validating, why, and how failure is handled.
Fix: Validate everything, both on the front end and server side. Sanitize inputs, escape outputs, and never trust client data by default.
3. Misconfigured Access Control
Applications often expose more than they should — especially during early development or staging phases. Forgotten debug endpoints, admin panels without proper authentication, or APIs that don’t restrict access properly can all lead to critical leaks.
In larger codebases, broken permission logic can also create privilege escalation vulnerabilities.
Fix: Apply the principle of least privilege across your system. Test not just if features work, but if they’re properly protected. Secure staging environments and disable access to debug tools before production.
4. Treating Security as an Afterthought
This is perhaps the root of all problems: security is often treated as someone else’s job, or as a final check just before launch.
But by the time your code hits QA, the most vulnerable parts may already be deeply embedded — in architecture, design patterns, or third-party dependencies.
Fix: Shift security left. Embed it in every phase of the development lifecycle. Talk about security during planning. Review code with a security lens. Automate what you can, document what you can’t.
Final Thought
None of these mistakes are new — and that’s exactly why they’re dangerous. They’ve been around for years, and yet they still show up in real-world apps and real-world breaches.
Security is a mindset, not a checklist. It’s built into habits, reviews, decisions, and culture.
Want to write better software?
Start thinking like someone trying to break it — before they actually do.