CVE-2026-0300
PAN-OS: Unauthenticated user initiated Buffer Overflow Vulnerability in User-ID™ Authentication Portal
- Published
- May 6, 2026
- Updated
- Jul 14, 2026
- Assigning CNA
- palo_alto
- Evidence observed
- May 6, 2026
Primary CVSS
nvd · CVSS 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:C/RE:M/U:RedModerate · next 30 days
- Percentile
- 98.3%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
CISA Known Exploited
This CVE appears in the CISA Known Exploited Vulnerabilities catalog.
Summary
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.
Sources
7Proof-of-concept for CVE-2026-0300, a critical buffer overflow in PAN-OS User-ID Portal enabling unauthenticated remote code execution with root privileges.
- POC-CVE-2026-0300-exploitExploit
Palo Alto - CVE-2026-0300 exploit
- CVE-2026-0300Exploit
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