You can crash someone's iPhone with a mere text message.

A nasty computer bug in Apple's iOS allows anyone who sends an iPhone a certain text message to shut it down.

The worst part? You don't even need to open the text message. Your device just needs to receive it.

That means anyone can pull off this prank -- and anyone whose mobile number is known by someone else is susceptible.

The nonsensical message includes two English words, a string of Arabic characters that appears to have no meaning, and a Japanese character.

Read this story on CNN Arabic

CNNMoney independently tested the message and can verify it works. You send the special text message -- and the receiving iPhone immediately crashes. It comes back on by itself after 15 seconds.

This isn't devastating, but it is annoying and Apple will make a fix available. But some users have already started complaining that an alternative version of the code permanently disables iMessage -- until you delete the conversation.

(One tip to get around this freeze is to use the Photos app to send a text message, then once you're in iMessage, erase the conversation.)

This hack was first discovered by users of the forum website Reddit, who think they figured out what's wrong.

Their theory: an error in the way iPhones display incoming messages. Reddit users who experimented with this say the iPhone's notification pop-up has trouble displaying that particular line of code. The device turns itself off so the machine won't completely crash.

But it's difficult to know what's wrong. Apple (AAPL) has not yet explained what's happening but said in a statement: "We are aware of an iMessage issue caused by a specific series of unicode characters, and we will make a fix available in a software update."

It's unclear if someone stumbled on this code by accident -- or was specifically looking for ways to wreak havoc.