FPDI is a collection of PHP classes that facilitate reading pages from existing PDF documents and using them as templates in FPDF. Prior to version 2.6.7, an attacker can upload a small, malicious PDF file that will cause the server-side script to crash due to memory exhaustion or a script time-out. Repeated attacks can lead to sustained service unavailability. This issue has been patched in version 2.6.7.

FPDI: Memory Exhaustion and Endless Loop in FPDI leads to Denial of Service