Ok I found a walkaround. I create a label on the front page and added the image with the "insert image" button. By looking at the code after I copied the url in the src attribute of the <img> tag (../draftfile.php/28/user/draft/918983208/icons.svg). I deleted the <img> tag but saved the empty label.
I was then able to reused this url everywhere I needed that same image.
Hope this could help someone else, someday !