A bug in the Android mobile operating system has been discovered by researchers, who say it affects nearly a billion devices. The flaw can be exploited by sending a photo or video message to a person's smartphone,
without any action by the receiver.
Google said it had patched the problem, but millions of devices still need their software updating.
The researchers said the flaw was "extremely dangerous".
Researchers from US information security company Zimpherium said they believed it was one of the worst Android vulnerabilities to date, estimating that 950 million devices were affected.