An Arbitrary Free (Remote Code Execution) issue was discovered in Design Science MathType 6.9c. Crafted input can overwrite a structure, leading to a function call with an invalid parameter, and a subsequent free of important data such as a function pointer or list pointer. This is fixed in 6.9d.
https://drive.google.com/open?id=1qrHKzDA1daHh0mM2T8FRybL8we-mHRW9