Less than a week a go, reports of a message capable of crashing PS4s started circulating around the internet. It would seem that the issue is now fixed on Sony’s end, and those who are still affected do not need to factory reset their consoles.
Based on a tweet by the Twitter account Ask PlayStation UK, those that are still affected can fix this on their own by deleting the offending message via the PS app, going into the PS4’s Safe Mode, and selecting option 5, which refers to rebuilding the database of the console.
We've since fixed the issue, and it wasn't bricking consoles, just sending them into a crash loop that can be quickly fixed in under 5 minutes. Delete the message on the PS mobile app, go into Safe Mode, use Option 5, console back to normal. ^DB
— Ask PlayStation UK (@AskPS_UK) October 15, 2018
Because there are no other details of the fix, it’s entirely possible for another message of similar nature to surface in the future. Of course, this means that the best way to prevent this from happening is to change your privacy settings so that strangers will not be able to send you messages.
(Source: Ask PLayStation UK / Twitter)