# CVE-2026-0300

## Summary

- **CVE ID:** CVE-2026-0300
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/AU:Y/R:U/V:C/RE:M/U:Red)
- **CWE:** CWE-787
- **Published:** May 6, 2026
- **Last Modified:** Jul 14, 2026

## Description

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.

## Affected Products

- Palo Alto Networks — Cloud NGFW (All)
- Palo Alto Networks — PAN-OS (12.1.0)
- Palo Alto Networks — PAN-OS (11.2.0)
- Palo Alto Networks — PAN-OS (11.1.0)
- Palo Alto Networks — PAN-OS (10.2.0)
- Palo Alto Networks — Prisma Access (All)

## References

- [CNA](https://security.paloaltonetworks.com/CVE-2026-0300)
- [CISA-ADP](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-967325.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 31.72%
- **EPSS Percentile:** 98.2

## Known Exploited Vulnerabilities (KEV)

- **Date Added:** May 6, 2026
- **Due Date:** May 9, 2026

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._