Google does send notices via Google Search Console to upgrade your WordPress install or other generic CMS platforms that are outdated. The other day, Google sent a boatload to those they think are running WordPress 4.9.3 that they should update that version as soon as possible because there is a security bug that is vulnerable to attack.
But some who received the notification are not running that version of WordPress and were confused by the message.
Google's Eric Kuan posted in the Google Webmaster Help forums that if you did receive this message in error that (1) you can ignore it and (2) you can let Google know which site it was for so they can improve these message notifications in the future.
Eric wrote:
Thanks for your feedback on the WordPress update message. We're working on making sure that the messages we send to users to update their CMSs are as accurate as possible. If you could let me know what sites you received a message for that are no longer on WordPres 4.9.3 or have already updated to a newer version, that will help us send more accurate messages.In the meantime if you already on a newer version of WordPress 4.9.3 or no longer use WordPress, feel free to ignore that message that came through in Search Console.
Barry Adams shared a screen shot of the message on Twitter:
So if you got the message in error, do let Google know.
Forum discussion at Google Webmaster Help.