| Package | Affected versions | Patched versions |
|---|---|---|
| budibase | < 3.39.9 | 3.39.9 |
| @budibase/server | < 3.39.9 | 3.39.9 |
The webhook trigger endpoint in Budibase is publicly accessible and passes the full HTTP request body into automation execution parameters. A mass assignment vulnerability in externalTrigger() allows an attacker to overwrite the internal appId property by including it in the webhook POST body. When the automation is processed asynchronously (the default path for webhooks without a collect step), the worker executes the attacker-defined automation in the context of the victim's workspace, granting full read/write access to the victim's database.
The webhook trigger route is registered as a public endpoint with no authentication:
// packages/server/src/api/routes/webhook.ts:12
publicRoutes.post("/api/webhooks/trigger/:instance/:id", controller.trigger)
The controller passes the raw request body as fields alongside the server-derived appId:
// packages/server/src/api/controllers/webhook.ts:142-148
await triggers.externalTrigger(target, {
fields: {
...ctx.request.body, // attacker-controlled
body: ctx.request.body,
},
appId: prodAppId, // server-controlled
})
In externalTrigger(), for webhook-triggered automations, params.fields is spread back into params:
// packages/server/src/automations/triggers.ts:237-241
params = {
...params, // appId: prodAppId (server-controlled)
...params.fields, // appId: VICTIM_ID (attacker-controlled, overwrites above)
fields: {},
}
Because params.fields is spread after params, any key in the attacker's body overwrites the corresponding property in params. An attacker including "appId": "app_VICTIM_WORKSPACE_ID" in the POST body overwrites the legitimate, server-derived appId.
The contaminated params become data.event and are queued asynchronously:
// packages/server/src/automations/triggers.ts:244,271
const data: AutomationData = { automation, event: params }
// ...
return quotas.addAction(() => automationQueue.add(data, JOB_OPTS))
The async worker uses job.data.event.appId to set the workspace context:
// packages/server/src/threads/automation.ts:917,929-930
const workspaceId = job.data.event.appId // attacker-controlled
// ...
return await context.doInAutomationContext({
workspaceId, // victim's workspace
automationId,
task: async () => { /* automation steps run here */ }
})
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Scan my site freeThe synchronous path (for webhooks with a collect step) correctly overwrites appId at triggers.ts:264:
data.event = {
...data.event,
appId: context.getWorkspaceId(), // server-controlled fix
automation,
}
This proves the developers intended appId to be server-controlled but missed applying the same fix to the async path, which is the default for all webhooks without a collect step.
Prerequisites: Attacker has builder access to their own Budibase workspace and knows a victim workspace ID (format: app_<uuid>).
Step 1: Attacker creates an automation in their own workspace with a webhook trigger and data-exfiltration steps (e.g., Query Rows → Execute Script to send data externally).
Step 2: Attacker creates a webhook for that automation and notes the webhook URL:
POST /api/webhooks/trigger/<ATTACKER_INSTANCE>/<WEBHOOK_ID>
Step 3: Attacker triggers the webhook with the victim's workspace ID injected into the body:
curl -X POST https://budibase.example.com/api/webhooks/trigger/app_ATTACKER_ID/wh_WEBHOOK_ID \
-H 'Content-Type: application/json' \
-d '{"appId": "app_VICTIM_WORKSPACE_ID", "normalData": "test"}'
Expected result: The automation defined in the attacker's workspace executes in the context of the victim's workspace. All database operations (Query Rows, Create Row, Delete Row, Execute Script, etc.) operate on the victim's data.
Additional overridable fields via the same mechanism:
timeout (automation.ts:443-444): override automation execution timeoutuser (automation.ts:413,435): set user context for automation stepsmetadata.automationChainCount (automation.ts:293): bypass chain depth limitsAn attacker with builder access to their own Budibase workspace can execute arbitrary automations (of their own design) in the context of any other workspace on the same Budibase instance, provided they know the victim's workspace ID. This enables:
The attack requires no authentication (the webhook endpoint is public) and leaves minimal audit trail since the automation execution is attributed to the attacker's automation definition but runs in the victim's context.
In packages/server/src/automations/triggers.ts, apply the same appId fix that exists in the synchronous path to the async path as well. The fix should ensure appId is always server-controlled before queuing:
// packages/server/src/automations/triggers.ts:244-272
const data: AutomationData = { automation, event: params }
// ... trigger filter check ...
+ // Ensure appId is always server-controlled, not user-supplied
+ data.event.appId = context.getWorkspaceId()
if (getResponses) {
data.event = {
...data.event,
appId: context.getWorkspaceId(),
automation,
}
return quotas.addAction(() =>
executeInThread({ data } as AutomationJob, { onProgress })
)
} else {
return quotas.addAction(() => automationQueue.add(data, JOB_OPTS))
}
Alternatively, use an allowlist approach for the webhook field spread to prevent any internal property from being overwritten:
// packages/server/src/automations/triggers.ts:237-241
const { appId, timeout, user, metadata, ...safeFields } = params.fields
params = {
...params,
...safeFields,
fields: {},
}