Galaxy S21 gets December 2025 security update in the US

Samsung is rolling out a software update to the Galaxy S21 series phones in the US. It offers the December 2025 security patch.

Samsung’s non-foldable flagship smartphones from 2021, the Galaxy S21, Galaxy S21+, and the Galaxy S21 Ultra, are on a quarterly security update schedule, which means that they will get one security update every quarter. Well, this quarter’s security update is here, and it brings the December 2025 security patch.

For now, the update is live for the carrier-locked variants of the Galaxy S21 series phones in the US. It carries firmware version G99xUSQSIHYL1. The December 2025 security patch fixes a total of 57 security issues. You can read more about it here. To get the update, go to Settings > Software update > Download and install.

Samsung launched the Galaxy S21 with One UI 3 (Android 11) and offered it five new versions of Android and One UI, with the most recent being One UI 8.0 (Android 16). However, it was the last major update for the three phones in the lineup. Samsung will not offer One UI 8.5 or future Android/One UI versions to these devices.

If that's making you think of upgrading to a new phone, now is a great time, as Samsung is offering massive discounts on the Galaxy S25 Ultra and the Galaxy Z Fold 7, on the occasion of Christmas/year-end. Speaking of which, check out our video below where we talk about the best Samsung products in 2025.

Abid Iqbal Shaik - Writer

First Samsung device: Galaxy S II

I’m a computer science engineer living in Hyderabad, India, who has a keen interest in automobiles and consumer electronics. My journalism career kicked off in 2017 with MySmartPrice where I wrote news, features, buying guides, and explanatory articles about technology among other things, and reviewed many products, including smartphones, tablets, laptops, PC components, smartwatches, audio devices, wearables, and smart home products. Since then, I have worked for 91Mobiles, Apple, and Onsitego, before finally landing on SamMobile.

Firmware Phone December 2025 Security Patch Galaxy S21 Galaxy S21 Plus Galaxy S21 Ultra USA