Samsung has started rolling out the latest security patch to its 2021 flagship lineup. The carrier-locked variants of the Galaxy S21, Galaxy S21+, and Galaxy S21 Ultra in the United States are now receiving the December 2025 security update.
The update arrives with firmware version G99xUSQSIHYL1. As the devices are now on a quarterly update schedule, this is the security patch for the current quarter. If you have a Galaxy S21, check for the latest update by navigating to Settings > Software update > Download and install.
The December 2025 security patch is a substantial update, addressing a total of 68 vulnerabilities. It incorporates Google’s fixes for 57 issues in the core Android OS, six of which are classified as critical. Samsung has also patched 11 security flaws specific to its software.
Related: Here’s why Galaxy S21 FE will get One UI 8 but other S21 models won’t
The Galaxy S21, S21+, and S21 Ultra launched with One UI 3.0 (based on Android 11) and has received four major Android OS upgrades, with the final one being the One UI 7.0, based on Android 15. While the devices are no longer eligible for major upgrades in the future, they will continue to receive security updates for a while.
