Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

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• NewsExploited · CISA KEVPalo Alto Networks · PAN-OS

  Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

  CVE-2026-0300

  Palo Alto Networks PAN-OS contains an out-of-bounds write vulnerability in the User-ID Authentication Portal (aka Captive Portal) service that can allow an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.

  CISA's required action · due 9 May 2026 for U.S. federal civilian agencies

  Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Until the vendor releases an official fix, the following workaround should be implemented: - Restrict User-ID Authentication Portal access to only trusted zones. - Disable User-ID Authentication Portal if not required. 5/13/2026: Palo Alto has released a variety of patches. If these are relevant to your environment, please apply the designated patch.

  Cited by CISA: security.paloaltonetworks.com · nvd.nist.gov

  Added to KEV 6 May 2026 · Source checked 4 Nov 2026, 16:35 UTC · CISA KEV entry

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