Out-of-bounds write in Palo Alto PAN-OS - CVE-2026-0300
Published: May 6, 2026 / Updated: August 14, 2026
Vulnerability identifier: #VU130217
CSH Severity: Critical
CVSS v4: 10 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H]
CVE-ID: CVE-2026-0300
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vulnerability details
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a boundary error within the User-ID Authentication Portal (aka Captive Portal) service. A remote attacker can send specially crafted packets to the device, trigger an out-of-bounds write and execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls.
Note, the vulnerability is being actively exploited in the wild.
Affected software
Palo Alto PAN-OS
How to mitigate CVE-2026-0300
Install update from vendor's website.
Palo Alto PAN-OS - addressed in versions 10.2.10-h36, 10.2.16-h7, 10.2.18-h6, 11.1.4-h33, 11.1.6-h32, 11.1.10-h25, 11.1.13-h5, 11.2.7-h13, 11.2.10-h6, 12.1.4-h5
Links to Public Exploits and PoC-codes
- Exploit #12891 - panos-captive-portal-rce (Scanner: CVE-2026-0300 PAN-OS User-ID Captive Portal Buffer Overflow RCE — Python CLI for detecting actively exploited BOF vulnerability in Palo Alto firewalls (CISA KEV 2026-05-13)) (August 14, 2026)
- Exploit #12724 - CVE-2026-0300-PANOS (Security Research and Proof-of-Concept (PoC) for CVE-2026-0300 : Unauthenticated Remote Code Execution (RCE) in Palo Alto Networks PAN-OS User-ID Portal.) (May 22, 2026)