CVE-2026-59387: high-severity vulnerability in Cloud Foundry CAPI (Cloud Controller API)

The Nginx routing configuration for Cloud Controller blocks unauthenticated access to /internal/v4/ and /internal/v5/ endpoints but omits an equivalent deny rule for /internal/v3/. As a result, the staging callback endpoints /internal/v3/staging/:guid/droplet_completed and /internal/v3/staging/:guid/build_completed are reachable from the public API listener without OAuth or mutual TLS.   An attacker with a valid build or droplet GUID can submit a forged staging callback, transition a droplet to STAGED, and persist arbitrary process metadata and sidecar data with no associated package or actor. A SpaceAuditor can enumerate GUIDs without write permissions, making this an effective privilege escalation beyond the intended role boundary.