CVE-2026-0300: Unauthenticated Buffer Overflow Leading to Root RCE in PAN-OS User-ID Authentication Portal
CVE-2026-0300 is a critical buffer overflow vulnerability in the User-ID Authentication Portal service, also known as Captive Portal, within PAN-OS. It allows unauthenticated remote attackers to send specially crafted packets and achieve arbitrary code execution with root privileges on affected PA-Series and VM-Series firewalls. The flaw stems from improper handling of input data in the authentication portal component, enabling out-of-bounds writes that corrupt memory and grant full system control.