CVE-2026-54351

Budibase: Mass Assignment in Webhook Trigger Allows Cross-Workspace Automation Execution via appId Override

// packages/server/src/api/routes/webhook.ts:12
publicRoutes.post("/api/webhooks/trigger/:instance/:id", controller.trigger)

// 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
})

// packages/server/src/automations/triggers.ts:237-241
params = {
  ...params,          // appId: prodAppId (server-controlled)
  ...params.fields,   // appId: VICTIM_ID (attacker-controlled, overwrites above)
  fields: {},
}

// packages/server/src/automations/triggers.ts:244,271
const data: AutomationData = { automation, event: params }
// ...
return quotas.addAction(() => automationQueue.add(data, JOB_OPTS))

// 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 */ }
})

data.event = {
  ...data.event,
  appId: context.getWorkspaceId(),  // server-controlled fix
  automation,
}

POST /api/webhooks/trigger/<ATTACKER_INSTANCE>/<WEBHOOK_ID>

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"}'

An 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:

• Full data exfiltration: Query Rows steps read all tables in the victim's workspace
• Data manipulation: Create Row, Update Row, Delete Row steps modify victim data
• Arbitrary code execution in victim context: Execute Script steps run JavaScript with access to victim's environment variables and database
• Cross-tenant boundary violation: In multi-tenant deployments (Budibase Cloud), the tenant ID is derived from the workspace ID, so the attack crosses tenant boundaries

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.

CVE-2026-54351 has a CVSS score of 8.2 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.39.9); upgrading removes the vulnerable code path.

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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: {},
}

1. What is CVE-2026-54351? CVE-2026-54351 is a high-severity security vulnerability in @budibase/server (npm), affecting versions < 3.39.9. It is fixed in 3.39.9.
2. How severe is CVE-2026-54351? CVE-2026-54351 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @budibase/server are affected by CVE-2026-54351? @budibase/server (npm) versions < 3.39.9 is affected.
4. Is there a fix for CVE-2026-54351? Yes. CVE-2026-54351 is fixed in 3.39.9. Upgrade to this version or later.
5. Is CVE-2026-54351 exploitable, and should I be worried? Whether CVE-2026-54351 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
6. What actually determines whether CVE-2026-54351 is exploitable, and how bad it is? 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.
7. How do I fix CVE-2026-54351? Upgrade @budibase/server to 3.39.9 or later.

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