Wazuh 5.0.0-beta1 (fixed in 5.0.0-beta3) does not validate or override the cluster_name and cluster_node fields in inventory-sync Start FlatBuffer messages, while validating only the agentid against the authenticated agent identity. This allows a low-privileged enrolled agent to spoof cluster attribution in indexed inventory and vulnerability documents by forging wazuh.cluster.name values and influencing the document _id prefix, potentially tampering with inventory records or, in shared-indexer multi-cluster deployments, poisoning another cluster's records when numeric agent IDs collide.