Palo Alto Networks Firewalls Hit by Unauthenticated GlobalProtect DoS Flaw

Palo Alto Networks has warned that a high-severity vulnerability in PAN-OS could allow an unauthenticated attacker to shut down firewalls protecting enterprise networks, with the flaw tracked as CVE-2026-0227 and a CVSS score of 7.7. The issue affects GlobalProtect Gateway and Portal features and requires specific configurations for exploitation; Cloud NGFW deployments are reportedly not affected.

According to the security advisory, “A vulnerability in Palo Alto Networks PAN-OS software enables an unauthenticated attacker to cause a denial of service (DoS) to the firewall”, and the flaw can force a firewall into maintenance mode, disrupting traffic until manual intervention.

The vulnerability spans multiple PAN-OS versions, including PAN-OS 12.1 (prior to 12.1.3-h3 and 12.1.4), PAN-OS 11.2 (prior to 11.2.7-h8 and 11.2.10-h2), and PAN-OS 10.2 (various builds requiring updates such as 10.2.7-h32, 10.2.10-h30, or 10.2.13-h18). Administrators are urged to upgrade to fixed versions: 12.1.4 or later for 12.1, 11.2.10-h2 or later for 11.2, and appropriate 10.2 targets depending on current patch level. For older, unsupported PAN-OS releases, the guidance is to upgrade to a supported fixed version.