A vulnerability in the PAN-OS software enables a remote attacker to reboot PAN-OS firewalls when receiving Windows New Technology LAN Manager (NTLM) packets from Windows servers. Repeated attacks eventually cause the firewall to enter maintenance mode, which requires manual intervention to bring the firewall back online. The issue is related to errors in input validation, allowing an attacker to cause a denial of service using specially crafted NTLM packets from Windows servers.