CVE-2026-46370: Fleet has observer-level enrollment secret extraction via ORDER BY oracle on labels host-listing endpoint

A vulnerability in Fleet’s labels host-listing endpoint allowed authenticated users with the lowest-privilege Observer role to extract host enrollment secrets (node_key, orbit_node_key) through a cursor-based binary search oracle. The endpoint accepted a user-supplied order_key parameter that was not validated against a column allowlist, permitting sort order to be driven by sensitive columns in a joined table.