GHSA-v42f-v8xc-j435

### Summary 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. ### Details **The guard pins the validated IP via a Node agent** — `packages/backend-core/src/utils/outboundFetch.ts`: - `resolveSafePinnedIp(url)` resolves the hostname and checks every address against `isBlacklisted`, returning a single `pinnedIp` (lines ~39–53). - `makePinnedAgent(url, ip)` builds a **Node** `http.Agent`/`https.Agent` whose `lookup` always returns `pinnedIp`, so a node-fetch connection can only reach the validated IP (lines ~55–68). - `fetchWithBlacklist` passes that agent into the request: `fetchFn(nextUrl, { ...nextRequest, agent: makePinnedAgent(nextUrl, pinnedIp) })` (lines ~186–192). Each r