Emacs version 25.3 had an emergency fix that solved a security vulnerability.

Very unlikely anyone will be ever targeted on the N900 but if you use emacs to receive mail (like me) it is probably not a bad idea to add the following to your init file.

(eval-after-load "enriched"
'(defun enriched-decode-display-prop (start end &optional param)
(list start end)))

That should fix the vulnerability for emacs <25.3
source here