CLASSIFICATION: CYBER THREAT ASSESSMENT CVE-2026-0300 represents a critical remote code execution vulnerability affecting Palo Alto Networks PAN-OS deployments across PA-Series and VM-Series platforms, exploitable by unauthenticated threat actors through malformed packets directed at the User-ID Authentication Portal service. The out-of-bounds write condition permits direct elevation to root-level code execution without credential requirements, establishing this vector as operationally significant for network perimeter compromise. Organizations operating affected firewall models should prioritize patch deployment and consider interim network segmentation measures pending remediation. This vulnerability has been catalogued within the CISA Known Exploited Vulnerabilities database, indicating evidence of active exploitation.