GHSA-v42f-v8xc-j435: Budibase: SSRF via DNS rebinding in the REST datasource integration

Budibase’s central outbound-fetch guard (fetchWithBlacklist) prevents SSRF/DNS-rebinding by resolving the target hostname, checking every resolved IP against the blacklist, and pinning the connection to the validated IP. The pin is implemented as a Node http(s).Agent (makePinnedAgent). The fix for CVE-2026-54353 relies on this pin to stop DNS rebinding.

The REST datasource integration (@budibase/server) calls fetchWithBlacklist but performs the actual request with undici’s fetch. undici does not support the Node agent option — it is silently ignored — and instead uses its own dispatcher, which re-resolves the hostname’s DNS at connection time. As a result, the validated/pinned IP is never used on the REST datasource path, and the DNS-rebinding protection that CVE-2026-54353 added is silently defeated for the single most-used outbound path in Budibase.

An authenticated user who can configure/run a REST datasource (e.g. a builder/tenant) can use a rebinding hostname (public IP during validation, internal IP at connect) to make the server issue arbitrary, full-response HTTP requests to internal-only services — cloud metadata (IAM credential theft), the internal CouchDB/Redis/MinIO, and other internal endpoints — reading and, because REST datasources allow arbitrary method/body, writing or destroying internal data.