A new era is beginning for Samsung’s legendary flagship models of 2021, the Galaxy S21, S21+, and S21 Ultra. Once regularly updated monthly, these devices have now transitioned to receiving security patches every three months. The latest update in this cycle, the December 2025 security update, has officially begun rolling out to users in the US.
December 2025 Patch: 57 Vulnerabilities Closed
With the new software build number G99xUSQSIHYL1, Samsung aims to maximize device security for the Galaxy S21 series.
Comprehensive Protection: This update eliminates a total of 57 system-wide security vulnerabilities.
Performance: While the new patch doesn’t introduce any visual improvements or additional features, it aims to optimize system stability and extend the device’s lifespan.
We have both good and somewhat bittersweet news for Galaxy S21 users. Samsung has kept its promise of four major Android updates for this series.
- Final Destination: The S21 family has completed its major software journey by receiving the latest Android 16-based One UI 8.0 update.
- Out of Scope: Samsung will not release One UI 8.5 or later Android versions for these models in the future. The devices will now only receive periodic security patches.
In February 2025, a decision was made to remove the Galaxy S21 series from the monthly update list and include it in the quarterly list. This means the devices are still supported, but Samsung’s focus has shifted to newer models (such as the Galaxy S25 and S26 series).
How to Update? If you own a Galaxy S21, to check if the update has reached your device:
- Go to the Settings menu.
- Tap the Software Update tab.
- Check using the Download and Install option.
