ClamAV AntiVirus software versions 0.99.2 and prior contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper input validation checking mechanisms in mbox.c during certain mail parsing functions of the ClamAV software. An unauthenticated, remote attacker could exploit this vulnerability by sending a crafted email to the affected device. An exploit could trigger a NULL pointer dereference condition when ClamAV scans the malicious email, which may result in a DoS condition.