Well, the issue here is that you can not be sure of what you have in your clipboard! I can think of 2 case scenarios that this can be a security issue:
- When a normal user copy the content from websites and paste directly into a vulnerable software (Microsoft Word?!) and the copied contents simply trigger the vulnerability.
- When an admin copy and paste some command directly from a website (tutorials?!) into their terminal! This is the creepy one cause depends on the privilege of admin (duh!!) it can download and execute scripts; and then to make things looks OK performs a cleanup and probably do what it supposed to do !!
The solution is not that difficult though: just be aware of what you paste, where you paste and think twice before you paste!! Perhaps just paste in a notepad first, or just get a clipboard manager!
P/S: You can find a simple demonstration here: