CVE-2026-27584 is a critical-severity missing authentication for critical function vulnerability in @actual-app/sync-server (npm), affecting versions < 26.2.1. It is fixed in 26.2.1.
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 integration that implements the authentication middleware (packages/sync-server/src/app-gocardless/app-gocardless.js): PoC The below commands exploit this vulnerability on both the SimpleFIN and Pluggy.ai endpoints. No authentication is required. Network access is required. SimpleFIN: PluggyAI: Example response from POST /simplefin/accounts: Example response from POST /simplefin/transactions:
A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.
npm
@actual-app/sync-server (< 26.2.1)@actual-app/sync-server → 26.2.1 (npm)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Already deployed Kodem? See CVE-2026-27584 in your environment →Upgrade @actual-app/sync-server to 26.2.1 or later to resolve this vulnerability.
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CVE-2026-27584 is a critical-severity missing authentication for critical function vulnerability in @actual-app/sync-server (npm), affecting versions < 26.2.1. It is fixed in 26.2.1. A critical operation is accessible without requiring any authentication.
@actual-app/sync-server (npm) versions < 26.2.1 is affected.
Yes. CVE-2026-27584 is fixed in 26.2.1. Upgrade to this version or later.
Whether CVE-2026-27584 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade @actual-app/sync-server to 26.2.1 or later.