No matter what document it is, if everyone can open it for editing, then your document has no privacy, and the contents inside will be seen by others. If you want to increase privacy, you need to set your own special password.

Only the uploaded data will be stored in the server, which is in danger of leakage. But you can encrypt the data, or encrypt the network disk. For example, the 360 network disk has a safe. If you don't know the encryption password, you can't open it even if you know the login password! Two layers of protection! The network is not safe now.

Take Microsoft office as an example, both word and excel have local code execution vulnerabilities, such as CVE-2017-1882 and CVE-20 18-0802. Attackers can hide vulnerable code in documents. When you open this document with vulnerable office, you will execute the code reserved by the attacker, such as opening a shell and binding a remote port to execute an exe.