ActualBudget server is Missing Authentication for SimpleFIN and Pluggy AI bank sync endpoints
Date: 2026-02
Affected: npm/@actual-app/sync-server
Attack vector: auth-bypass
Category: vulnerability-disclosure
Severity: Critical
CVE: CVE-2026-27584
CWE: CWE-306

### Summary Missing authentication middleware in the ActualBudget server component allows any unauthenticated user to query the SimpleFIN and Pluggy.ai integration endpoints and read sensitive bank account balance and transaction information. ### Impact This vulnerability allows an unauthenticated attacker to read the bank account balance and transaction history of ActualBudget users. This vulnerability impacts all ActualBudget Server users with the SimpleFIN or Pluggy.ai integrations configured. The ActualBudget Server instance must be reachable over the network. ### Details The ActualBudget server component allows for integration with SimpleFIN and Pluggy.ai services. These services read bank account balances and transaction data from users' banks and return the data to ActualBudget. The affected endpoints facilitate this integration and are intended to be used only by logged in users for the purposes of syncing bank transaction data. The vulnerable source code is in the following files in the `actualbudget/actual` GitHub repository (https://github.com/actualbudget/actual/): * `/packages/sync-server/src/app-simplefin/app-simplefin.js` * `/packages/sync-server/src/app-pluggyai/app-pluggyai.js` The sensitive endpoints missing authentication are: * `POST /simplefin/status` * `POST /simplefin/accounts` * `POST /simplefin/transactions` * `POST /pluggyai/status` * `POST /pluggyai/accounts` * `POST /pluggyai/transactions` The following source code is an example of an integ


Mitigations:

Architectural layers (MAESTRO):