Samsung Galaxy S21 users were a bit surprised to receive an update in November 2025. Earlier in the year, Samsung demoted the S21 line — models that are about five years old — to quarterly updates. That’s why users were surprised to see another update ahead of the expected quarterly schedule of every three months — January, April, July, and October.

Despite the new quarterly update schedule, Samsung Galaxy S21, Galaxy S21 Plus, and S21 Ultra users got a security update in November 2025. This update doesn’t add any new features or visuals but rather provides Galaxy S21 users with better security thanks to the arrival of firmware version G99xBXXSIHYK1. The fingerprint sensor was improved with further accuracy, and the USB connection was given further security when plugged into different devices and chargers. Some Samsung users were relieved to see the unexpected security update, while others feel frustrated that the Galaxy S21 has been reduced to quarterly updates.

Samsung makes the most Android smartphones out of any carrier. Like most phones, Android devices can be targeted by hackers. Over the years, various hacking incidents have exploited the vulnerabilities of Android phones in an attempt to obtain user data. Even Samsung’s older Android devices must continue to receive security updates to ensure users are safe from newly discovered exploits.

To check if your older Samsung device has a security update, open the Settings app, navigate to “Software Update,” and then click “Download” if a security update is available. Owners of older devices may have to check the “About Device” section of the Settings app. Devices that are five years old will still receive security updates, but models older than the Galaxy S21 were released when Android only offered three years of support and no longer receive updates. These old devices are often vulnerable to hacks and other security issues so you may want to consider upgrading, maybe to a newer Samsung Galaxy option.