- Critical 9.3
- Known exploited (CISA KEV)
CVE-2026-0300
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 applian…
Scores
The facts
- Published
- 6 May 2026
- Last changed
- 17 June 2026
- NVD status
- Analyzed
- Severity
- Critical, CVSS 9.3 out of 10 (version 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… - Weakness
- Affects
- paloaltonetworks pan-os
- siemens ruggedcom ape1808 firmware
- Known exploited
- Yes. CISA added it to the Known Exploited Vulnerabilities catalogue on 6 May 2026.
- EPSS
- 31.7% chance of exploitation activity in the next 30 days (percentile 98).
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