Summary: MMS messages can cause Android phones to decode video with libstagefright, which is a C++ library with vulnerabilities and insufficient sandboxing, leading to remote code execution without user interaction.
You can partially mitigate the risk by disabling auto-downloading of MMS messages in whichever app you have set to handle text messages, such as Messaging or Hangouts. THIS IS URGENT. While the precise details of the flaw have not been publicly disclosed, this disclosure is sufficient for a skilled person to rediscover the flaw, which means that there is a considerable risk that someone will systematically use it on all the phone numbers.
You can partially mitigate the risk by disabling auto-downloading of MMS messages in whichever app you have set to handle text messages, such as Messaging or Hangouts. THIS IS URGENT. While the precise details of the flaw have not been publicly disclosed, this disclosure is sufficient for a skilled person to rediscover the flaw, which means that there is a considerable risk that someone will systematically use it on all the phone numbers.