The problem is if you click the insert hyperlink button in IE 10 and IE 11 you will receive the drop down menu to enter the url, but you can not set focus on the textbox to enter a URL. everytime you click on the box the focus goes inside the below content editable
How to repro:
Open this link http://mindmup.github.io/bootstrap-wysiwyg/ in IE 10 and IE 11, click on the icon to add link and click on the URL box and try entering something
Similar to Aamir's solution, you can also solve this using the following JavaScript snippet.