Palo Alto Networks has disclosed a critical buffer overflow vulnerability (CVE-2026-0300, CVSS 9.3) in the PAN-OS User-ID Authentication Portal. This flaw allows unauthenticated remote attackers to execute arbitrary code with root privileges on affected PA-Series and VM-Series firewalls, with limited active exploitation already observed in the wild.
CVE-2026-0300
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Security Advisory 2026-006 Cyber Centre Daily Advisory Digest — 2026-05-06 (3 advisories) The Canadian Centre for Cyber Security released a daily digest highlighting three security advisories. The most critical is an actively exploited, unauthenticated buffer overflow vulnerability (CVE-2026-0300) affecting the Palo Alto Networks PAN-OS User-ID Authentication Portal. Additional routine security updates were announced for Google Chrome and VMware Tanzu GemFire Management Console.
CISA Adds One Known Exploited Vulnerability to Catalog CISA has added CVE-2026-0300, an out-of-bounds write vulnerability affecting Palo Alto Networks PAN-OS, to its Known Exploited Vulnerabilities (KEV) Catalog due to evidence of active exploitation. Organizations are strongly urged to prioritize remediation to reduce exposure to cyberattacks.
