CVE-2026-0227 is a high-severity denial-of-service vulnerability affecting Palo Alto Networks PAN-OS and Prisma Access deployments where GlobalProtect Gateway or Portal is enabled.
The flaw allows an unauthenticated remote attacker to repeatedly trigger a condition that forces the firewall into maintenance mode, resulting in loss of availability. While no data exposure or integrity impact is involved, the vulnerability directly affects a critical security control and can disrupt remote access, perimeter enforcement, and network availability.
What It Is
Palo Alto Networks describes CVE-2026-0227 as an improper handling of unusual or exceptional conditions within PAN-OS when processing GlobalProtect-related traffic. Repeated triggering of this condition causes the firewall to transition into maintenance mode.
From an attacker’s perspective, this is a pure availability attack: no credentials, no exploitation chain, and no post-exploitation actions are required. The attacker’s objective is simply to degrade or disable firewall services by forcing repeated service interruptions.
Impact
The primary impact of CVE-2026-0227 is service disruption.
Affected firewalls may repeatedly enter maintenance mode, leading to intermittent or sustained outages. In environments that rely on GlobalProtect for remote access, this can result in widespread VPN downtime, loss of connectivity for remote users, and disruption to business-critical workflows.
Because the vulnerability affects perimeter security infrastructure, exploitation can also indirectly weaken an organization’s security posture by temporarily removing inspection, enforcement, and access control capabilities during outages.
Affected Systems
This issue applies only to PAN-OS and Prisma Access deployments with GlobalProtect Gateway or Portal enabled.
Affected versions include multiple PAN-OS releases prior to the following fixed versions:
- PAN-OS 12.1: fixed in 12.1.3-h3 and 12.1.4 or later
- PAN-OS 11.2: fixed in 11.2.4-h15, 11.2.7-h8, or 11.2.10-h2 and later
- PAN-OS 11.1: fixed in 11.1.4-h27, 11.1.6-h23, 11.1.10-h9, or 11.1.13 and later
- PAN-OS 10.2: fixed in 10.2.7-h32, 10.2.10-h30, 10.2.13-h18, 10.2.16-h6, or 10.2.18-h1 and later
- PAN-OS 10.1: fixed in 10.1.14-h20 and later
Cloud NGFW is not affected.
Prisma Access is affected until upgraded to 11.2.7-h8 or 10.2.10-h29, with upgrades rolling out per Palo Alto Networks’ standard process.
Exploitation Status
Palo Alto Networks has stated that it is not aware of malicious exploitation of CVE-2026-0227 at the time of publication.
However, the availability of a proof-of-concept, combined with unauthenticated access and low attack complexity, suggests the vulnerability is well-suited for opportunistic or nuisance-level attacks, particularly against organizations with exposed GlobalProtect portals.
Recommended Actions
Patch as a priority
Apply the relevant PAN-OS or Prisma Access fixed version as outlined by Palo Alto Networks. There are no effective workarounds or configuration-based mitigations for this issue.
Validate GlobalProtect exposure
Review whether GlobalProtect gateways and portals are exposed only where operationally required, and confirm that unused services are disabled.
Monitor for service instability
Watch for unexpected firewall restarts, maintenance mode transitions, or abnormal GlobalProtect-related events that may indicate attempted abuse.
Stay Safe. Stay Secure.
OP Innovate Research Team
