Vulnerability Analysis
PAN-OS: Unauthenticated user initiated Buffer Overflow Vulnerability in User-ID™ Authentication Portal
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 appliances are not impacted by this vulnerability.
CISA KEV
SSVC: Active Exploitation
Automatable
CVSS Base Score
9.3
CRITICAL
Exploitability:-
Impact Score:-
Temporal Score:-
EPSS:32.07%
Threat Intelligence Signals
CISA KEV
YES
KEV Date Added
2026-05-06
Ransomware Use
Unknown
KEV Due Date
2026-05-09
VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
32.074%
EPSS Percentile
98.1th pct
GHSA ID
GitHub Severity
CRITICAL
SSVC Exploitation
Active
SSVC Automatable
Yes
Vulnerability Class
—
Identity & Timeline
| Status | - |
| Assigning Authority | - |
| CVSS Version / Source | - |
| Reserved | - |
| Published | - |
| Patch Date (date_public) | - |
| Exploit DB Date | - |
| First GitHub PoC Date | - |
| Last Updated | - |
| Time to Patch (Days to fix) | - |
| Exploit Release Gap | - |
| PoC Release Gap | - |
| Exploit DB References | None identified |
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| No affected products specified. | ||
Social Buzz