AT&T Galaxy S5 OTA Update version G900AUCU4BOF3, Fixes for Stagefright bug

AT&T has just announced the release of  a new update on Galaxy S5 SM-G900A. The update will be sent out via Over-the-Air and dubbed with build version G900AUCU4BOF3.  The latter include a security patch to fix the Stagefright bug that surrounds on some infected apps that one have had downloaded and a website that was  just designed to bug any Android smartphones and tablets when a user visits on it.
AT&T released a software update for the Samsung Galaxy S 5 (SM-G900A) on August 5, 2015. The update is available to customers to download via Firmware Over The Air (FOTA). Wi-Fi is required for the update.

Below is the technical details about the update:
  • Android version: 5.0
  • Baseband version: G900AUCU4BOF3
  • Kernel version: 3.4.0-4432708
  • Build number: LRX21T.G900AUCU4BOF3
  • Upgrade file size: 301MB

The update has just started as we speak. So make sure to check the update manually if you did not receive any notification yet. Just tap on Settings>About device>Software update>Check for update. You may also head over to AT&T's Galaxy S5 support page for further details about the update.
Also, keep in mind that your device should not have been rooted or have modified system images so you'll get the update without any hiccups.

Source: AT&T S5 support, Samsung S5 support