A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.
The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses.
Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.
Published: 2026-05-06
CVSS: 9.8
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Download CVE-2026-0300 POC (Proof-of-Concept) here:
Tip: Download official Tor Browser at https://www.torproject.org/download/ to access .onion links.
https://hokyo.gr/poc-113-cve-2026-43056/
https://hokyo.gr/poc-461-cve-2026-43112/
https://hokyo.gr/poc-580-cve-2026-7913/
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