Zone Alarm contains a flaw in Email Protection that may allow a malicious user to bypass email attachement filename filter. The issue is triggered when foreign characters or parens is used in filenames (c - è, s - ¹, z - ¾). The attachement will not be qurarantined. It is possible that the flaw may allow a remote attacker to bypass ZoneAlarm and send arbitrary malwares in email attachemnt, resulting in a loss of integrity.
Upgrade to version 5.0 or higher, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.