Description

Palo Alto Networks has warned customers about a critical security flaw affecting its PAN-OS firewall platform. The vulnerability, identified as CVE-2026-0300, is linked to the User-ID Authentication Portal service and can allow remote attackers to gain root-level code execution without authentication. Threat actors can exploit the flaw by sending specially crafted network traffic to vulnerable devices. According to the advisory, the risk is highest when the User-ID Authentication Portal is exposed to the internet or other untrusted networks, where the vulnerability receives a CVSS score of 9.3. Systems with portal access limited to trusted internal networks face slightly lower risk. Palo Alto Networks confirmed that real-world exploitation attempts have already been observed against exposed firewall instances. Several versions of PAN-OS 10.2, 11.1, 11.2, and 12.1 are impacted. Security updates for the issue are expected to begin rolling out on May 13, 2026. Until fixes become available, organizations should reduce exposure by limiting portal access to internal trusted zones or disabling the feature if it is unnecessary. Additional security measures such as network segmentation, strict access controls, and reducing public-facing services can help minimize the likelihood of successful attacks.