Wazuh cluster worker file sync allows arbitrary file write under /var/ossec (incomplete fix for CVE-2026-30893)

Summary

Wazuh is an open-source security platform providing unified XDR and SIEM protection for endpoints and cloud workloads. In versions 4.4.0 through 4.14.6, a party holding the cluster key can write, overwrite, or delete arbitrary files under /var/ossec on worker nodes, leading to remote code execution as root. During cluster file synchronization, the non-merged branch of update_master_files_in_worker() moves each staged file to a destination derived only from safe_join(), which confines the path to /var/ossec but never verifies that the file lands in the directory declared by its cluster_item_key. Because the destination check present on the primary node and on the worker's merged branch was not applied, a peer can place files at attacker-chosen locations under /var/ossec, including paths that are executed as root, and the delete branch has the same gap. This is an incomplete fix for CVE-2026-30893, which addressed traversal outside /var/ossec but left this path able to redirect files anywhere within it. This issue is fixed in version 4.14.7.