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.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.7
- CVSS vector
- 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
- EPSS probability
- 31.72%
- CISA KEV
- Known exploited vulnerability
- CWE
- CWE-787
- Published
- 2026-05-06
- Last modified
- 2026-07-14
Affected products
- Palo Alto Networks Cloud NGFW
- Palo Alto Networks PAN-OS
- Palo Alto Networks PAN-OS
- Palo Alto Networks PAN-OS
- Palo Alto Networks PAN-OS
- Palo Alto Networks Prisma Access
Weakness type
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