Fix SQL Injection (Legacy & Modern) in Polka
Polka is a minimalist Express-like framework, but its lack of middleware bloat doesn't protect you from the oldest trick in the book: SQL Injection. If you are manually concatenating user-controlled input from 'req.params' or 'req.query' into your SQL strings, you are inviting data exfiltration and remote code execution via stacked queries. This guide covers the shift from dangerous string interpolation to hardened parameterized queries.
The Vulnerable Pattern
const polka = require('polka'); const { Pool } = require('pg'); const pool = new Pool();
polka() .get(‘/api/user/:id’, async (req, res) => { const { id } = req.params; // VULNERABLE: Direct string interpolation allows OOB input to manipulate the AST const query =SELECT username, email FROM users WHERE id = ${id}; try { const result = await pool.query(query); res.end(JSON.stringify(result.rows)); } catch (err) { res.statusCode = 500; res.end(err.message); } }) .listen(3000);
The Secure Implementation
The legacy approach fails because it treats user input as part of the SQL command structure, allowing an attacker to inject payloads like '1; DROP TABLE users--'. The modern fix utilizes 'Prepared Statements' via the database driver. By passing the query and the data separately, the database driver ensures that the input is properly escaped and typed before execution. For high-scale Polka apps, consider using an abstraction layer like Prisma or Kysely which provides type-safe query building, effectively eliminating raw SQLi vectors at the compile level.
const polka = require('polka'); const { Pool } = require('pg'); const pool = new Pool();polka() .get(‘/api/user/:id’, async (req, res) => { const { id } = req.params; // SECURE: Use Parameterized Queries (Prepared Statements) // The engine treats $1 as a literal value, not executable SQL code. const text = ‘SELECT username, email FROM users WHERE id = $1’; const values = [id];
try { const result = await pool.query(text, values); if (result.rows.length === 0) { res.statusCode = 404; return res.end('Not Found'); } res.end(JSON.stringify(result.rows[0])); } catch (err) { res.statusCode = 500; res.end('Internal Server Error'); }
}) .listen(3000);
Your Polka API
might be exposed to SQL Injection (Legacy & Modern)
74% of Polka apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
Free Tier • No Credit Card • Instant Report
Verified by Ghost Labs Security Team
This content is continuously validated by our automated security engine and reviewed by our research team. Ghost Labs analyzes over 500+ vulnerability patterns across 40+ frameworks to provide up-to-date remediation strategies.