# 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.

- Page: https://www.vulneraibility.com/cve/CVE-2026-0300
- CVSS: 9.8
- Known exploited: yes, in CISA KEV since 2026-05-06; CISA due date 2026-05-09
- EPSS: 41.71%
- Unvetted proof-of-concept code on GitHub: 10 GitHub proofs of concept (first 2026-05-06)
- CISA SSVC: exploitation active, automatable yes, technical impact total (assessed 2026-05-06)
- Weakness: CWE-787
- Published: 2026-05-06

## Affected versions

- Palo Alto Networks PAN-OS: affected >= 12.1.0 and < 12.1.7; >= 11.2.0 and < 11.2.12; >= 11.1.0 and < 11.1.15; >= 10.2.0 and < 10.2.18-h6

A version outside these ranges is not a statement that it is unaffected.

## References

- [advisory] https://security.paloaltonetworks.com/CVE-2026-0300
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300
- [other] https://cert-portal.siemens.com/productcert/html/ssa-967325.html

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.