GHSA-rgvg-3wpc-h44p: Budibase: Mass Assignment in Webhook Trigger Allows Cross-Workspace Automation Execution via appId Override

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: // 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: // packa