Your NFS Server Doesn’t Actually Check Who You Are. It Just Trusts You.
NFSv4’s default authentication mechanism, AUTH_SYS, doesn’t actually verify user identity โ it blindly trusts UID/GID claims from the client machine. The ‘secure’ mount option only marginally mitigates local unprivileged spoofing while doing nothing against root-level or cross-network impersonation. If you’re running NFS without explicitly configuring Kerberos, your files are accessible to anyone who can spoof a UID.