Galaxy S5 AT&T Finally rooted “towelroot” – Hoping for CyanogenMod next!
Using a recently discovered Linux kernel vulnerability, geohot has managed to root the Verizon Samsung Galaxy S 5.
The root exploit itself is built around Linux kernel CVE-2014-3153, which was recently discovered by hacker Pinkie Pie, and it involves an issue in the Futex subsystem that in turn allows for privilege escalation. Although expressly released for the Verizon Galaxy S5, the root exploit will realistically be compatible with practically every device with an unpatched kernel–which at this point should be nearly every device not running a recent nightly build of a custom ROM with a patched kernel. As such, it has also already been tested and found to work with the AT&T Galaxy S5, Nexus 5, Galaxy S4 Active, and AT&T and Verizon variants of the Note 3.
As a site note, this method should work with any Android device with a kernel date before June 3, 2014. Certain HTC and Motorola devices are exempt because of the way they mount the system partition, though. If anything, it might be worth trying on your phone if you've been dying for root and are willing to accept the responsibility for anything that might go wrong.
You can find more information on his original thread at XDA Developers forums