This indicates an attack attempt to exploit a Use After Free Vulnerability in Foxit Software PDF Reader.
This vulnerability is due to improper handling of Annotation objects. A remote attacker could exploit this vulnerability by enticing a victim user to visit a malicious web page or open a crafted PDF document. Successful exploitation could allow the attacker to execute arbitrary code under the security context of the user.
Foxit Software PDF Editor 10.1.4.37651 and earlier
Foxit Software PDF Editor 220.127.116.11893 and earlier
Foxit Software PDF Reader 18.104.22.168893 and earlier
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.