Hatchet is a platform for orchestrating background tasks, AI agents, and durable workflows at scale. From 0.40.0 until 0.91.1, the Dispatcher gRPC service does not verify that a request's worker ID belongs to the tenant identified by the bearer-token context in Dispatcher/UpsertWorkerLabels and Dispatcher/Unsubscribe. An authenticated owner of any tenant who guesses another tenant's worker UUID can overwrite that worker's affinity labels or disconnect the worker from the dispatcher. This can cause cross-tenant integrity impact and denial of service on multi-tenant Hatchet Cloud or shared self-hosted deployments. Single-tenant deployments are not practically affected because the attacker and target tenant are the same. This issue is fixed in version 0.91.1.