libMariaS3 uses libcurl underneath. This in-turn uses an SSL library which most commonly is OpenSSL. Certain versions of Linux compile it with OpenSSL 1.0.2 which has a potential race condition in it.
To resolve this the curl creators recommend adding locking callbacks to OpenSSL. Of course this requires us to know what SSL library Curl was compiled with. Which means once there is a code fix to libMariaS3 there will also need to be a subsequent fix in the S3 engine's build system.