Amazon RDS for MariaDB supports new minor versions 10.2.37, 10.3.28, 10.4.18, and 10.5.9.

Amazon Relational Database Service (Amazon RDS) for MariaDB now supports MariaDB minor versions 10.2.37, 10.3.28, 10.4.18, and 10.5.9. We recommend that customers upgrade to the latest minor versions to fix known security vulnerabilities in prior versions of MariaDB, and to benefit from the numerous bug fixes, performance improvements, and new functionality added by the MariaDB community. Amazon RDS customers can leverage automatic minor version upgrades to automatically upgrade their databases to the latest minor version during scheduled maintenance windows. Learn more about upgrading your database instances, including automatic minor version upgrades, in the Amazon RDS User Guide.

Source:: Amazon AWS