CVE-2026-0300

9.8 CRITICAL CISA KEV - Actively Exploited
Published: May 06, 2026 Modified: May 12, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://security.paloaltonetworks.com/CVE-2026-0300
Source: psirt@paloaltonetworks.com
Mitigation Vendor Advisory
https://cert-portal.siemens.com/productcert/html/ssa-967325.html
Source: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.8 / 10.0
EPSS (Exploit Probability)
14.4%
94th percentile
Exploitation Status
Actively Exploited
Remediation due: 2026-05-09

Weaknesses (CWE)

Affected Vendors

paloaltonetworks siemens