This indicates an attack attempt to exploit a Memory Corruption vulnerability in MatrixSSL.
The vulnerability is due to an error when the vulnerable software attempts to improper validate a user-supplied key size. An attacker can exploit this by crafting special X.509 certificate and execute arbitrary code within the context of the application.
MatrixSSL before 4.0.2
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.