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CVE-2026-0300

9.8, critical Known exploited

Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
32% higher than 98.2% of scored CVEs
Exploitation
Confirmed in the wild
Published
6 May 20265 months ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 6 May 2026. US federal agencies had to remediate by 9 May 2026, a deadline that has passed.

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.

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.

Details

Vendor
Palo Alto Networks and 1 more
Product
Cloud NGFW
Weakness
CWE-787 (opens in a new tab)
Status
Analyzed
Updated
17 Jun 2026
Assigner
psirt@paloaltonetworks.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References 3

Advisories 2

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Palo Alto Networks CVEs

Every Palo Alto Networks CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-0322 Palo Alto Networks PAN-OS Code Injection Vulnerability KEV EPSS 1% 7.2, high
  • CVE-2026-0257 Palo Alto Networks PAN-OS Authentication Bypass Vulnerability KEV EPSS 97% 9.1, critical
  • CVE-2025-0108 Palo Alto Networks PAN-OS Authentication Bypass Vulnerability KEV EPSS 98% 9.1, critical
  • CVE-2025-0111 Palo Alto Networks PAN-OS File Read Vulnerability KEV EPSS 2% 6.5, medium
  • CVE-2024-3393 Palo Alto Networks PAN-OS Malicious DNS Packet Vulnerability KEV EPSS 29% 7.5, high
  • CVE-2024-0012 Palo Alto Networks PAN-OS Management Interface Authentication Bypass Vulnerability KEV EPSS 100% 9.8, critical
  • CVE-2024-9474 Palo Alto Networks PAN-OS Management Interface OS Command Injection Vulnerability KEV EPSS 95% 7.2, high
  • CVE-2024-9463 Palo Alto Networks Expedition OS Command Injection Vulnerability KEV EPSS 99% 7.5, high

Beyond this page

Is CVE-2026-0300 in your network?

This page tells you how dangerous CVE-2026-0300 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2026-0300 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-0300 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.