In MariaDB before 10.9.2, compress_write in extra/mariabackup/ds_compress.cc does not release data_mutex upon a stream write failure, which allows local users to trigger a deadlock.
MariaDB v10.2 to v10.7 was discovered to contain a segmentation fault via the component Exec_time_tracker::get_loops/Filesort_tracker::report_use/filesort.