Improper check for certificate revocation in i-FILTER Ver.10.45R01 and earlier, i-FILTER Ver.9.50R10 and earlier, i-FILTER Browser & Cloud MultiAgent for Windows Ver.4.93R04 and earlier, and D-SPA (Ver.3 / Ver.4) using i-FILTER allows a remote unauthenticated attacker to conduct a man-in-the-middle attack and eavesdrop on an encrypted communication.