Is Firebase safe?
Firebase's security rules are the entire defense. Misconfigure them and the whole app is open. Here is how to get it right.
Firebase is safe when security rules are strict. The most common failure mode is default-allow rules committed at the project root of Firestore or Realtime Database.
How it fails in production
Default-allow Firestore rules
A rule like `allow read, write: if true` at the root means every document is public.
Cloud Functions without auth check
Callable functions default to unauthenticated. Missing `context.auth` check = public admin function.
Admin SDK in client bundle
The Admin SDK bypasses every rule. Client-side exposure = full compromise.
How to ship safely on Firebase
- Scope every Firestore / Realtime rule by auth.uid and tenant
- Require context.auth in every Cloud Function
- Admin SDK never in client code — server only
- Enable Firebase App Check for production
Securie's Firebase specialist validates every rules file + every Cloud Function for auth coverage + detects Admin SDK in client paths.
Verdict
Firebase is safe with strict rules. Default-allow rules are the single most common fatal mistake.