A newly discovered security flaw on iOS can cause the Messages app to crash when a specific string of text is sent in a text message, causing some phones to lock and reboot.
The SMS reset message, first shared on Reddit and later on social media, seems to work regardless of the device it's sent from.
According to The Verge, if you have your Messages app open when you receive the text, you won’t be able to reopen the conversation without the Messages app crashing.
If you receive the text message, you can reply to the text message using Messages on a Mac to prevent the app from continuously crashing. If you don't have a Mac, you can ask Siri to send a reply to the text message from your "friend," which should allow you to re-open the Messages app.
You can also call the "friend" who sent you the text message and ask them to send you a second text message, which should also allow you back into your Messages app.
Apple has not commented on the security flaw as of Wednesday morning.