Fix Command Injection in Qwik
Command injection in Qwik frameworks typically manifests within 'server$' closures or route loaders where Node.js primitives are accessible. If you are piping user-controlled props directly into shell-executing functions, you are handing over a shell to the attacker. Here is how to kill that bug.
The Vulnerable Pattern
import { server$ } from '@builder.io/qwik'; import { exec } from 'child_process';
export const getSystemLogs = server$(async (filename: string) => { // VULNERABLE: Direct concatenation into shell command // Attacker can pass: ‘log.txt; rm -rf /’ return new Promise((resolve) => { exec(cat ./logs/${filename}, (err, stdout) => { resolve(stdout); }); }); });
The Secure Implementation
The vulnerability exists because 'exec' spawns a subshell (/bin/sh or cmd.exe), causing it to interpret shell metacharacters like semicolons or pipes. By switching to 'spawn' with 'shell: false', the arguments are passed directly to the binary's argv array without shell parsing, neutralizing payload execution. Additionally, implementing a strict Regex allow-list ensures that only expected characters reach the logic, following the principle of Defense in Depth.
import { server$ } from '@builder.io/qwik'; import { spawn } from 'child_process';export const getSystemLogs = server$(async (filename: string) => { // 1. Strict Input Validation (Allow-list) if (!/^[a-zA-Z0-9._-]+$/.test(filename)) { throw new Error(‘Illegal characters detected’); }
// 2. Use spawn() instead of exec() to avoid shell interpretation return new Promise((resolve, reject) => { const child = spawn(‘cat’, [
./logs/${filename}], { shell: false, timeout: 5000 });let output = ''; child.stdout.on('data', (data) => output += data); child.on('close', () => resolve(output)); child.on('error', (err) => reject(err));
}); });
Your Qwik API
might be exposed to Command Injection
74% of Qwik apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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