CVE-2026-84298: Hatchet: Cross-tenant durable callback payload disclosure in Hatchet V1 Dispatcher

The V1 DurableTask stream handler registers worker-supplied durable task external IDs in an in-memory callback routing map before verifying that the authenticated tenant owns the task. If the tenant-scoped ownership check fails, the handler logs the error and continues, but the map entry persists until the stream closes.

Durable callback delivery resolves the destination stream by task_external_id only, without checking tenant identity. As a result, a tenant A worker that knows a tenant B durable task external UUID can hold its stream open and receive tenant B’s durable callback result payload when the callback is delivered on the same dispatcher process.