Tell me about a time you identified and resolved a critical security vulnerability or compliance risk.

In Simple Words: Highlight security hygiene: proactive vulnerability scanning, responsible disclosure, defense-in-depth, and automated regression testing.

The STAR Response:

• Situation: While reviewing an open-source dependency update, I audited our tenant-scoped API routes and noticed that one endpoint was vulnerable to Insecure Direct Object Reference (IDOR)—an authenticated user could pass another customer's organizationId in the request body to retrieve confidential invoice data.
• Task: Patch the vulnerability immediately across all API endpoints, verify whether data was breached, and institute automated prevention.
• Action:
  1. Immediately patched the controller to enforce row-level security: deriving tenantId strictly from the cryptographically signed JWT token rather than the user-supplied payload.
  2. Queried our historical CloudWatch logs to verify whether any malicious access had occurred (confirmed zero unauthorized access).
  3. Created an automated security integration test suite using Supertest that attempts cross-tenant data requests on every API route during CI.
  4. Led a team lunch-and-learn on OWASP Top 10 API Security vulnerabilities.
• Result: Eliminated the IDOR vulnerability across all services and ensured that any future attempt to access cross-tenant data without authorization is automatically caught in CI before deployment.

Practical Script & Summary Template

// Enforcing tenant isolation at the repository level:
export async function getInvoicesForTenant(userJwt: { organizationId: string }, invoiceId: string) {
  // NEVER trust invoiceId alone from req.params; ALWAYS bind to authenticated tenantId!
  return db.invoices.findOne({
    where: {
      id: invoiceId,
      organizationId: userJwt.organizationId // Derived strictly from verified server-side JWT
    }
  });
}