The Samsung Galaxy Note 4 is getting an OTA update today, and it takes the device from 5.0 up to 5.1.1. That means a few small tweaks to the system, but there are also some important bug fixes, including one for the Stagefright vulnerability.
Here's the changelog posted by Samsung.
- Android version 5.1.1, Lollipop OS Upgrade
- Message Waiting Indicator fix
- Security fix (Stagefright)
- Misc. bug fixes.
The Stagefright bug was partially revealed last week and allowed mainstream news to once again run their 'all Android phones are in imminent danger' headline. It's a vulnerability in the Stagefright media handler component that can be used to exploit a phone via MMS. Nexus updates are supposed to start rolling out this week, and Sprint/Samsung are apparently wasting no time. However, some other devices may have gotten Stagefright patches prior to the official reveal (it's been known within the OHA for a few months).
We don't know if the update is available to everyone immediately or if it's staged. You can head into the settings and check manually if you want. No promises, though.