Luca Todesco, a developer, has found a loophole in the OS X 10.10.5 update released by Apple that can get a hacker root access of a Mac computer.

Todesco shared the information on Github and the loophole works on all versions of OS X Yosemite.
The developer did not give Apple a heads up before putting the information out on the internet and so Apple will not be immediately able to patch the vulnerability found by Todesco.
The vulnerability found by the developer is similar to the DYLD_PRINT_TO_ACCESS vulnerability which took Apple less than a month to fix.
Until the update comes out, Apple users can protect themselves by only downloading apps from the Apple Store and trusted developers.