Host overwrite is a condition in which software running outside the trusted host path replaces or modifies a file on the host system. In security terms, the key issue is not just file change, but who caused it and what trust boundary was crossed. If an external process can write to a host file, it may tamper with configuration, startup scripts, scheduled tasks, or application data.
This matters in container and virtualization environments because copy, sync, and extraction features sometimes bridge isolated content into the host filesystem. If path handling, symlinks, or overwrite checks are weak, a seemingly routine file-transfer operation can become a host overwrite risk. Attackers may use that to alter behavior, persist, or set up privilege escalation if the replaced file is security-sensitive. Defenders reduce exposure by restricting privileged copy operations, validating destination paths, and treating any write from a lower-trust source as a potential boundary violation.