Yes. Non-recursive CTEs in July 2016, and recursive CTEs in September 2016.
https://mariadb.com/kb/en/the-mariadb-library/mariadb-1021-r... https://mariadb.com/kb/en/the-mariadb-library/mariadb-1022-r...
https://mariadb.com/kb/en/the-mariadb-library/mariadb-1021-r... https://mariadb.com/kb/en/the-mariadb-library/mariadb-1022-r...