Jeez! A guy can’t be away from the Internet for a couple of days without everything changing. One of those changes is that a new version of Emacs, version 25.3, has been released. This is an emergency release to fix a security issue with Enriched Text mode.
You can read the details in the announcement but it’s probably a good idea to upgrade even if, like me, you aren’t using the X support. I did my usual compile-from-source dance without any problems.