Disable Clipboard Manipulations in Firefox

There are times when we copy some words from a webpage and find something new when we paste it, usually with some copyright related messages. See below as an example:

Test page:

cnet clipboard manipulations

The problem is:

The original source page listens to copy, paste and cut events and adds something into your clipboard.

The solution is simple:

 locate dom.event.clipboardevents.enable preference item in Firefox about:config, and set it to false (default is true)

This will prevent watching behaviour towards copy, paste and cut event, thus, the original pages don’t know what you have copied, or we can say: they won’t be informed when you copied something.


Here is a video showing how it works :

If you don’t want to get your hands dirty with Firefox advanced settings, you can try this add-on:

Disable clipboard manipulations Firefox addon


  1. flaz14   •  

    Thank you very much for this post, Jeriff!

    I’ve looked about how to get protected from Pastejacking attacks ( After applying your snippet the demo described there doesn’t work (so I get

    echo “not evil”

    without any additional symbols after copy-paste).

    Seems that for 100% protection Document.execCommand() should be disabled for actions ‘cut’, ‘copy’ and ‘paste’ (BTW does anybody know how to disable these actions in Firefox settings, without any addons installed?). But anyway your tip helps in major number of cases!

  2. Yongd   •  


  3. Jiangshui   •  

    Your new theme looks so high big up!

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