This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit PhantomPDF. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the handling of the WillClose action. A specially crafted PDF with a WillClose action can force a dangling pointer to be reused after it has been freed. An attacker can leverage this vulnerability to execute arbitrary code under the context of the current process.