There are missing EditorOnPaste modes in the DNN editor provider:

 

 if (Operators.CompareString(text2, "ConfirmWord", false) == 0)
    {
        this.cntlCE.EditorOnPaste = PasteBehavior.ConfirmWord;
    }
    else if (Operators.CompareString(text2, "PasteWord", false) == 0)
    {
        this.cntlCE.EditorOnPaste = PasteBehavior.PasteWord;
    }
    else if (Operators.CompareString(text2, "PasteText", false) == 0)
    {
        this.cntlCE.EditorOnPaste = PasteBehavior.PasteText;
    }
    else if (Operators.CompareString(text2, "Disabled", false) == 0)
    {
        this.cntlCE.EditorOnPaste = PasteBehavior.Disabled;
    }
    else
    {
        this.cntlCE.EditorOnPaste = PasteBehavior.Default;
    }

I was specifying inside web.config EditorOnPaste="PastePureText". I have compiled a custom editor provider to fix my issue, but you'll probably want to take a look at this.