CVE-2026-54351

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

Published

2026-06-22

Modified

2026-07-21

EPSS percentile

37%

Aliases

GHSA-rgvg-3wpc-h44p

Sources

github-advisory

Summary

## Summary 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. ## Details The webhook trigger route is registered as a public endpoint with no authentication: ```typescript // 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`: ```typescript // 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`: ```typescript // 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: ```typescript // 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: ```typescript // 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 */ } }) ``` The synchronous path (for webhooks with a collect step) correctly overwrites `appId` at `triggers.ts:264`: ```typescript 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. ## PoC **Prerequisites:** Attacker has builder access to their own Budibase workspace and knows a victim workspace ID (format: `app_ `). **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/ / ``` **Step 3:** Attacker triggers the webhook with the victim's workspace ID injected into the body: ```bash 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 aut

Affected packages

Remediation: Upgrade to 3.39.9 or later.

References

• https://github.com/advisories/GHSA-rgvg-3wpc-h44p