MariaDB Server before 10.7 is vulnerable to Denial of Service. In extra/mariabackup/ds_compress.cc, when an error occurs (i.e., going to the err label) while executing the method create_worker_threads, the held lock thd->ctrl_mutex is not released correctly, which allows local users to trigger a denial of service due to the deadlock. Note: The vendor argues this is just an improper locking bug and not a vulnerability with adverse effects.