A improper verification of source of a communication channel in Fortinet FortiOS with IPS engine version 7.201 through 7.214, 7.001 through 7.113, 6.001 through 6.121, 5.001 through 5.258 and before 4.086 allows a remote and unauthenticated attacker to trigger the sending of "blocked page" HTML data to an arbitrary victim via crafted TCP requests, potentially flooding the victim.