CVE-2026-87857CVE-2026-87857

Temporal Server does not bind a workflow-history pagination token to the namespace and workflow named in the request that presents it. GetWorkflowExecutionHistory and GetWorkflowExecutionHistoryReverse authorize the caller against the namespace in the request, then select history from the branch recorded inside the caller-supplied next_page_token. The normal history continuation carries a run identifier, event bounds, a persistence cursor, and a branch token, but no namespace or workflow identity, and it is serialized as unauthenticated protobuf bytes. An authenticated caller holding read permission on one namespace, together with a genuine non-final continuation issued earlier for a workflow in a second namespace, can submit that continuation with a request naming the first namespace and receive the second namespace's workflow history, provided the supplied workflow identifier selects the same History shard as the continuation's branch. No workflow with the supplied identifier needs t