If you don't have the latest versions of iOS or OS X on your Apple devices, you might want to go ahead and get on that.
Security vulnerabilities that can allow hackers to access your device by sending you an iMessage are found in almost every version of iOS and OS X, except the latest ones, report Forbes and Quartz.
Discovered by a researcher from Cisco, a hacker could send you a .TIF file (which is a photo file, like .jpg) that, when received, can execute a code that gives the hacker access to your device's internal storage and stored passwords.
In order to avoid this, there are a few simple solutions for the moment: you can update your devices to the latest versions, iOS 9.3.3 or El Capitan 10.11.6, or turn off iMessage.
Apple didn't immediately respond to requests for comment.