MariaDB Server before 10.7 is vulnerable to Denial of Service. In extra/mariabackup/ds_compress.cc, when an error occurs (pthread_create returns a nonzero value) while executing the method create_worker_threads, the held lock is not released correctly, which allows local users to trigger a denial of service due to the deadlock.
https://github.com/MariaDB/server/commit/e1eb39a446c30b8459c39fd7f2ee1c55a36e97d2