Exploited CVEs / Palo Alto Networks / CVE-2026-0300
CVE-2026-0300
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2026-05-09 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Palo Alto Networks Security Advisories, linked below.
Actively exploited Palo Alto Networks PAN-OS vulnerability, Critical severity, CVSS 9.8. Added to the CISA KEV catalog 2026-05-06.
Risk summary
Updated July 26, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2026-0300
An out-of-bounds write in the PAN-OS User-ID Authentication Portal, also known as Captive Portal, lets an unauthenticated attacker execute code as root on PA-Series and VM-Series firewalls. It is Critical at CVSS 9.8 with a 36% EPSS score, and exploitation was confirmed on 2026-05-06. Only firewalls with the Captive Portal service enabled expose the vulnerable path, which narrows the target set but makes those devices urgent.
Do this: Identify firewalls running Captive Portal, patch them first, and disable the portal where it is not actually needed.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-0300
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2026-0300
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
CISA required action
Federal (BOD 22-01) remediation due date: 2026-05-09 (past due).
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Until the vendor releases an official fix, the following workaround should be implemented: - Restrict User-ID Authentication Portal access to only trusted zones. - Disable User-ID Authentication Portal if not required. 5/13/2026: Palo Alto has released a variety of patches. If these are relevant to your environment, please apply the designated patch.
Official fix for CVE-2026-0300
The authoritative fix and affected-version list are published by the vendor. Find the PAN-OS advisory on Palo Alto Networks Security Advisories.
Common questions about CVE-2026-0300
Is CVE-2026-0300 actively exploited?
Yes. CVE-2026-0300 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2026-05-06, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 32%.
What is the CISA deadline and required action for CVE-2026-0300?
CISA set the federal (BOD 22-01) remediation due date at 2026-05-09, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Until the vendor releases an official fix, the following workaround should be implemented: - Restrict User-ID Authentication Portal access to only trusted zones. - Disable User-ID Authentication Portal if not required. 5/13/2026: Palo Alto has released a variety of patches. If these are relevant to your environment, please apply the designated patch.
What fixes CVE-2026-0300?
The authoritative fix is in the vendor advisory: see Palo Alto Networks Security Advisories for the patched PAN-OS versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2026-0300?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2026-0300's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).
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Authoritative references
Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.
