Broken Access Control
Last updated: January 16, 2026
Broken access control occurs when applications don't properly enforce restrictions on what authenticated users can do, allowing access to unauthorized functions or data.
Scan for This VulnerabilityWhat is Broken Access Control?
Even after authentication, users should only access resources and functions they're authorized for. Broken access control lets regular users access admin functions, view other users' data, or perform privileged operations. This is #1 on OWASP Top 10.
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 broken access control particularly prevalent in vibe-coded applications.
Understanding the Technical Details
Broken Access Control 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
- Client-side access control only
- Missing authorization checks on APIs
- Insecure direct object references
- Privilege escalation through parameter tampering
- Missing function-level access control
Impact
Unauthorized data access
Privilege escalation to admin
Data modification or deletion
Complete application compromise
How to Detect
- Test accessing resources with different user roles
- Try admin endpoints with regular user tokens
- Modify user IDs in requests
- Run VAS to test access controls
How to Fix
Implement server-side authorization
Never rely on client-side checks alone.
// Every API endpoint should verify authorization
export async function handler(req) {
const user = await getUser(req);
// Check authentication
if (!user) {
return res.status(401).json({ error: 'Unauthorized' });
}
// Check authorization
if (!user.roles.includes('admin')) {
return res.status(403).json({ error: 'Forbidden' });
}
// Proceed with admin action
}Use RLS for data access control
Let the database enforce row-level permissions.
-- Only admins can access admin_data
CREATE POLICY "Admin access only" ON admin_data
FOR ALL TO authenticated
USING (
EXISTS (
SELECT 1 FROM user_roles
WHERE user_id = (select auth.uid())
AND role = 'admin'
)
);Deny by default
Explicitly grant permissions, don't rely on absence of denial.
// Middleware that denies by default
function checkPermission(requiredPermission) {
return async (req, res, next) => {
const user = req.user;
// Default deny
if (!user?.permissions?.includes(requiredPermission)) {
return res.status(403).json({ error: 'Forbidden' });
}
next();
};
}
// Usage
app.delete('/users/:id', checkPermission('users:delete'), deleteUser);Commonly Affected Platforms
Prevention Best Practices
The most effective approach to broken access control 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?
VAS automatically scans for broken access control and provides detailed remediation guidance with code examples. Our scanner specifically targets vulnerabilities common in AI-generated applications.
Scans from $5, results in minutes. Get actionable results with step-by-step fix instructions tailored to your stack.
Get Starter ScanFrequently Asked Questions
What's the difference between authentication and authorization?
Authentication verifies WHO you are (login). Authorization verifies WHAT you can do (permissions). Broken access control is an authorization failure - the user is authenticated but accessing things they shouldn't. Both are required for security.
How does RLS help with access control?
RLS (Row Level Security) enforces authorization at the database level. Every query automatically includes permission checks. Even if your API has bugs, RLS ensures users only see/modify rows they're authorized for. It's defense in depth.