Samsung has widened the rollout of its December 2025 security patch, and the Galaxy S21 series is the latest to officially join the list. However, as these devices approach the end of their software support lifecycle, this update likely marks one of the final chapters for the former flagships.

The Galaxy S21, S21+, and S21 Ultra have started receiving the update in the US market, identified by firmware version G998USQSIHYL1. This patch focuses on fixing approximately 68 security vulnerabilities identified by Samsung, Google, and other partners, aimed at bolstering system security and overall stability.

Unsurprisingly, this update brings no new features, serving strictly as a security maintenance release. The S21 lineup is currently running on Android 15, which stands as the final major OS version Samsung committed to for these devices. Since the series missed the cut for the Android 16-based One UI 8—and consequently, One UI 8.5—Samsung has begun scaling back update frequency. The complete end of support is likely on the horizon.

The narrative is slightly different for the Galaxy S21 FE. Launching later than its siblings, the "Fan Edition" is currently running One UI 8 based on Android 16. According to the roadmap, it remains eligible for the One UI 8.5 update (based on Android 16 QPR2) in the first half of 2026. However, the road ends there; the S21 FE will not see Android 17. The stable One UI 8.5 release is expected to arrive alongside the Galaxy S26 series at the Galaxy Unpacked event in early 2026.

Galaxy S21 owners can check for the update by navigating to Settings > Software update > Download and install. Once the download finishes, select Install now. Users are advised to ensure their device has sufficient battery life and is not overheating before initiating the process.