CVE-2026-54746: Hatchet allows cross-tenant write/DoS to other tenants' workers via Dispatcher gRPC UpsertWorkerLabels and Unsubscribe

A cross-tenant write / DoS vulnerability in the Hatchet Dispatcher gRPC service allows any holder of a normal tenant-scoped API token (the lowest credential Hatchet issues — an OWNER of a brand-new tenant) to overwrite the affinity labels of, or disconnect from the dispatcher, any worker UUID belonging to any other tenant on the same Hatchet instance. The two affected RPCs — Dispatcher/UpsertWorkerLabels and Dispatcher/Unsubscribe — read the caller’s tenant from the bearer-token context only for analytics and response shaping, and never use it to authorise the worker_id from the request body.