This indicates an attack attempt against a NULL pointer Dereference Vulnerability in OpenSSL.
The vulnerability is caused by an error when the vulnerable application handles maliciously crafted DHE and ECDHE parameters. A remote attacker may be able to exploit this to cause a denial of service condition or execute arbitrary code on affected systems.
OpenSSL Project OpenSSL 1.1.x prior to 1.1.0d
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.