Windows – How to access raw clipboard data on Windows

You can see the different types by running the clipboard as record in AppleScript Editor.

the clipboard, the clipboard as text, or Unicode text of (the clipboard as record) will return a plain text version. AppleScript still converts line endings to CR though.

It is not secure.

See this question & answer on Security.stackechange.com, quoted below:

The Windows clipboard is not secure.

This is a quote from a MSDN article.

The Clipboard can be used to store data, such as text and images. Because the Clipboard is shared by all active processes, it can be used to transfer data between them.

This should probably apply to Linux machines as well.

Is this a concern? No. For someone to exploit this, he would have to have malware on your machine capable of reading data from the clipboard. If he has the capability of getting malware on your machine, you have much bigger things to worry about as there are plenty of other stuff he can do, including keyloggers and the like.