The latest software update for Galaxy S21 series mainly brings the April 2022 security patch, making it more secure by fixing different kinds of vulnerabilities. The OTA update for Galaxy S21, Galaxy S21+, and Galaxy S21 Ultra come with the firmware version G991BXXS4CVCG, G996BXXS4CVCG, and G998BXXS4CVCG, respectively. Samsung has not yet detailed the April 2022 security patch. So, we don’t know which vulnerabilities are getting patched here. Usually, the company reveals it in the first week of the month.
For now, the April 2022 security update for Galaxy S21 series is rolling out in Germany. And, it should not take more than a week for the update to start hitting more regions. If you are a Samsung Galaxy S21, Galaxy S21+ source
