CVE-2026-0300

A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets. The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses. Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.

Affected products

Pa-Series, Pan-Os, Vm Series

Paloaltonetworks Pan-os

= 10.2.0, 10.2.1, 10.2.2, 10.2.3, 10.2.4, 10.2.5, 10.2.6, 10.2.7, 10.2.8, 10.2.9, 10.2.10, 10.2.11, 10.2.12, 10.2.13, 10.2.14, 10.2.15, 10.2.16, 10.2.17, 10.2.18, 11.1.0, 11.1.1, 11.1.2, 11.1.3, 11.1.4, 11.1.5, 11.1.6, 11.1.7, 11.1.8, 11.1.9, 11.1.10, 11.1.11, 11.1.12, 11.1.13, 11.1.14, 11.2.0, 11.2.1, 11.2.2, 11.2.3, 11.2.4, 11.2.5

Fix

Available

CVSS 3.1

9.8 CRITICAL

EPSS

32.1% (98th percentile)

Weakness

CWE-787

NVD status

Analyzed

Published

2026-05-06

Attack patterns

CAPEC-100