A use-after-free vulnerability exists in the JavaScript engine of Foxit Software's PDF Reader, version 12.1.1.15289. A specially crafted PDF document can trigger the reuse of previously freed memory by manipulating form fields of a specific type. This can lead to memory corruption and arbitrary code execution. An attacker needs to trick the user into opening the malicious file to trigger this vulnerability. Exploitation is also possible if a user visits a specially crafted, malicious site if the browser plugin extension is enabled.