Every Input Is an Attack Vector: A Developer's Guide to Input Validation

Every form field, query parameter, URL slug, file upload, and HTTP header your application accepts is an attack surface. If you're not validating and sanitizing all of them, you have vulnerabilities. This isn't a question of "if" — it's a question of how many. We have linters for code style, type checkers for safety, test frameworks for correctness. But input validation? Most teams rely on frameworks to handle it, and frameworks only cover the happy path. I built InputShield to scan for input validation failures that standard linting tools miss. Here are the 6 most dangerous patterns it catches. 1. SQL Injection — Still Alive in 2026 ORMs handle most queries. But there's always that one raw query for a complex join or a search feature. // The pattern — string concatenation in SQL app . get ( ' /search ' , ( req , res ) => { const query = \ `SELECT * FROM products WHERE name LIKE '% ${ req . query . q } %' \` ; db.query(query); // SQL injection }); // The fix — parameterized queries, al