This indicates an attack attempt to exploit a Heap based Buffer Overflow in multiple Foxit products.
The vulnerability is due to improper bound checking when the vulnerable application converts a PNG file to PDF. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application via a crafted file.
Foxit Software Enterprise Reader 126.96.36.1995 and prior
Foxit Software Foxit Reader 188.8.131.525 and prior
Foxit Software PhantomPDF 184.108.40.2065 and prior
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor