Budibase: SSRF in Automation Steps - Webhook, Zapier, N8N, Slack, Discord Bypass IP Blacklist

Summary

Budibase automation steps (outgoing webhook, Zapier, n8n, Slack, Discord, Make.com) make server-side HTTP requests to user-provided URLs using node-fetch directly, completely bypassing the IP blacklist protection that exists in the REST API integration. Additionally, the REST API blacklist itself defaults to empty when BLACKLIST_IPS is not configured.

Vulnerable

Code

Automation

Steps (No Blacklist)

All automation steps use fetch() directly without any IP validation:

**packages/server/src/automations/steps/outgoingWebhook.ts line 69:** ``typescript const response = await fetch(url, request) // No blacklist check ``

**packages/server/src/automations/steps/zapier.ts line 34:** ``typescript response = await fetch(url, {method: "post", ...}) // No blacklist check ``

**packages/server/src/automations/steps/n8n.ts line 53:** ``typescript response = await fetch(url, request) // No blacklist check ``

**packages/server/src/automations/steps/slack.ts line 20:** ``typescript response = await fetch(url, {method: "post", ...}) // No blacklist check ``

**packages/server/src/automations/steps/discord.ts line 29:** ``typescript response = await fetch(url, {method: "post", ...}) // No blacklist check ``

REST

API Integration (Empty Default Blacklist)

**packages/server/src/integrations/rest.ts line 684:** ``typescript if (await blacklist.isBlacklisted(url)) { throw new Error("Cannot connect to URL.") } ``

But BLACKLIST_IPS env var defaults to undefined, so the blacklist is empty:

**packages/backend-core/src/blacklist/blacklist.ts lines 39-45:** ``typescript if (blackListArray?.length === 0) { return false // Always passes when no IPs configured } ``

Impact

• Automation steps: ANY user can create automations with webhook/Zapier/n8n/Slack/Discord steps pointing to internal IPs. These completely bypass the blacklist module
• REST API: Even when BLACKLIST_IPS is configured, it only blocks listed IPs. Default deployments have no protection.
• Cloud metadata: http://169.254.169.254/latest/meta-data/ accessible via any automation step
• Internal services: Access databases, admin panels, Kubernetes API on private IPs

Remediation

1. Apply blacklist checks to ALL outbound HTTP requests, including automation steps
2. Add hardcoded default private IP ranges (127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16)
3. Use a centralized HTTP client wrapper instead of direct fetch() calls
4. SSRF protection should be on by default, not opt-in via environment variable