A newly discovered (7/7/2015) exploit in OSX, the operating system used to power all Mac desktop and laptop products allows an attacker to gain root access (the most powerful user/admin account on a Unix, Linux or OSX) and subsequently access and change all files in the operating system pretty much at will.
All current versions of OSX are affected with the exception of the next version of OSX named El Capitan (OSX 10.11) which is currently in beta (testing).
Users are advised to upgrade if possible to the latest version of OSX 10.11 when it becomes available Q3 2015. In the meantime installing SUIDGuard (highly complex extension to the core of OSX) is the only other fix until Apple presents a patch hopefully soon.
This is potentially a very severe exploit with no clear path for an immediate fix that can be applied by the average user.
All owners and users of OSX are advised to be extra cautious, ensure that all updates are applied and monitor the OSX Yosemite website for availability of the next operating system. Also backing up your mac ASAP using Time Machine or Acronis True Image 2015 for Mac is highly recommended.
iPhone, iPod, iPad, Apple Watch and Apple TV products do not seem to be affected.
Original Story on Theregister.co.uk
Report from Stefan Esser, security researcher that discovered the vunerability.