Command Injection
Last updated: January 16, 2026
Command injection allows attackers to execute arbitrary system commands by injecting shell metacharacters into application inputs that are passed to system shells.
Scan for This VulnerabilityWhat is Command Injection?
When applications pass user input to shell commands without proper sanitization, attackers can inject shell metacharacters (;, |, &&, etc.) to execute additional commands. This can lead to complete server compromise.
Why It's Dangerous
This vulnerability can allow attackers to access sensitive data, compromise user accounts, or gain unauthorized control over your application. In AI-generated code, this issue is particularly common because security measures are often deprioritized in favor of rapid feature development.
Why AI Code Is Vulnerable
AI code generation tools focus on producing functional code quickly. They often generate patterns that work correctly but lack the defensive measures experienced security engineers would implement. This makes command injection particularly prevalent in vibe-coded applications.
Understanding the Technical Details
Command Injection is classified as a critical-severity vulnerability because of its potential to cause significant damage to your application and users. Understanding the technical mechanics helps you recognize and prevent this issue in your own code.
This vulnerability typically occurs when security controls are either missing entirely, improperly configured, or incorrectly implemented. In many cases, the code appears to work correctly during development and testing, but the security flaw becomes exploitable once the application is deployed and accessible to malicious actors.
Attackers actively scan for this type of vulnerability using automated tools. Once discovered, exploitation can be rapid—often within hours of your application going live. The consequences range from data theft and account takeover to complete system compromise depending on the application's architecture.
For vibe-coded applications built with platforms like Lovable, Bolt.new, Replit, or v0.dev, this vulnerability appears in roughly 20-40% of deployments according to security research. The AI-generated patterns often follow insecure defaults that require manual security hardening.
How It Happens
- Passing user input to shell commands
- Using shell: true in child_process
- Insufficient input validation
- String concatenation in commands
Impact
Complete server compromise
Data theft or destruction
Malware installation
Lateral movement in network
Cryptocurrency mining
How to Detect
- Review code for shell command execution
- Test inputs with shell metacharacters
- Check for exec, spawn, system calls
- Run security scanners
How to Fix
Avoid shell commands when possible
Use native libraries instead of shell commands.
// BAD - shell command for file operations
exec(`rm -rf ${userDir}`);
// GOOD - use fs module
import { rm } from 'fs/promises';
await rm(userDir, { recursive: true });Use parameterized execution
Pass arguments as array, not string.
// BAD - string concatenation
exec(`convert ${inputFile} ${outputFile}`);
// GOOD - argument array (no shell)
import { execFile } from 'child_process';
execFile('convert', [inputFile, outputFile]);
// Or spawn without shell
spawn('convert', [inputFile, outputFile], { shell: false });Strict input validation
Whitelist allowed characters if shell is necessary.
// Only allow alphanumeric and specific chars
const sanitized = input.replace(/[^a-zA-Z0-9_.-]/g, '');
// Or reject entirely
if (!/^[a-zA-Z0-9_.-]+$/.test(input)) {
throw new Error('Invalid input');
}Commonly Affected Platforms
Prevention Best Practices
The most effective approach to command injection is prevention. Implementing security measures during development is significantly easier and less costly than remediating vulnerabilities after deployment.
Security-First Development
When using AI code generation tools, always review the generated code for security implications. AI tools prioritize functionality over security, so treat all generated code as requiring security review. Establish a checklist of security requirements specific to your application type and verify each before deployment.
Continuous Security Testing
Integrate security scanning into your development workflow. Run scans after major code changes, before deployments, and on a regular schedule for production applications. Early detection of vulnerabilities reduces remediation costs and prevents potential breaches.
Defense in Depth
Never rely on a single security control. Implement multiple layers of protection so that if one control fails, others still protect your application. For example, combine authentication, authorization, input validation, and output encoding to create comprehensive protection against attacks.
Stay Informed
Security threats evolve constantly. Follow security researchers, subscribe to vulnerability databases, and monitor your dependencies for known issues. Understanding emerging threats helps you proactively protect your applications before attackers exploit new techniques.
Is Your App Vulnerable?
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Get Starter ScanFrequently Asked Questions
How do I know if my app is vulnerable?
Search your codebase for: exec(), execSync(), spawn() with shell:true, system(), popen(). If any of these use user input without strict validation, you may be vulnerable. Test by injecting ; id or | cat /etc/passwd in inputs.
Is execFile safer than exec?
Yes. exec() uses a shell and is vulnerable to injection. execFile() runs the command directly without a shell, so shell metacharacters aren't interpreted. Always prefer execFile() or spawn() without shell:true when executing commands.