Firebase Security Rules misconfiguration occurs when rules allow unauthorized access, commonly due to leaving test mode enabled or writing overly permissive rules.
Scan for This VulnerabilityFirebase Security Rules control access to Firestore and Realtime Database. Test mode rules (allow read, write: if true) expose your entire database publicly. Unlike traditional backends, Firebase relies entirely on these rules for security since the database is directly accessible from the client.
Complete database exposure - all data readable
Data manipulation - anyone can write/delete data
Potential data ransom attacks
Privacy violations and compliance failures
Service abuse and billing issues
Replace test mode rules with proper authentication checks.
// BAD - Test mode (NEVER deploy this)
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if true;
}
}
}Require authentication and check resource ownership.
// GOOD - Production rules
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /users/{userId} {
allow read, write: if request.auth != null
&& request.auth.uid == userId;
}
match /posts/{postId} {
allow read: if request.auth != null;
allow write: if request.auth != null
&& request.auth.uid == resource.data.authorId;
}
}
}Check that incoming data matches expected structure.
allow create: if request.auth != null
&& request.resource.data.keys().hasOnly(['title', 'content', 'authorId'])
&& request.resource.data.title is string
&& request.resource.data.title.size() <= 100;VAS automatically scans for firebase security rules misconfiguration and provides detailed remediation guidance.
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