The Galaxy S21 series may have reached the end of its major upgrade journey, but it hasn’t been abandoned. While the 2021 flagships won’t get One UI 8, Samsung has now released the latest security patch for them. Galaxy S21 series receives the September security updateSamsung is rolling out the September 2025 security update to the Galaxy S21, S21+, and S21 Ultra in the US. The update comes with the firmware build version HYI1 and appears to bring nothing more than the latest security fixes. Launched in early 2021, the Galaxy S21 phones are now on their last legs.