iPhones can be crashed if they receive a text containing one specific line of Arabic characters and symbols.

Sending the letters in a text message causes the phone to crash and then power off, leaving the Messages app unusable once the iPhone turns back on. Users have found a way of fixing the problem once it has happened, but there appears to be no way to keep phones from being vulnerable to it happening again until Apple sends out an update.

If users open the Messages app and the problem text is still open, users can just send a reply to fix the problem. If it's not, users must either receive a message or send a message to themselves, using Siri or by texting from the "share" option that can be found in many apps.

Users may be able to avoid the problem by turning off notifications for text messages, or hiding the previews that show up in banner notifications.

The problem appears to come from the way that the phone tries to show the message in notifications. The characters cause that system to break, so that it briefly tries to show it before crashing and then re-setting the phone in an attempt to fix it.

The text was found by Reddit users, who also discovered how the problem was affecting phones. The issue seems to have been around since iOS 6, users said, which was released in 2012.