CVE-2026-0300
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability - [Actively Exploited]
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.
INFO
Published Date :
May 6, 2026, 7:16 p.m.
Last Modified :
May 6, 2026, 8:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CISA KEV (Known Exploited Vulnerabilities)
For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.
Palo Alto Networks PAN-OS contains an out-of-bounds write vulnerability in the User-ID Authentication Portal (aka Captive Portal) service that can allow an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.
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.
Unknown
https://security.paloaltonetworks.com/CVE-2026-0300 ; https://nvd.nist.gov/vuln/detail/CVE-2026-0300
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | CRITICAL | d6c1279f-00f6-4ef7-9217-f89ffe703ec0 | ||||
| CVSS 4.0 | HIGH | d6c1279f-00f6-4ef7-9217-f89ffe703ec0 | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update PAN-OS software to the latest version.
- Secure User-ID portal access per guidelines.
- Restrict access to trusted internal IP addresses only.
Public PoC/Exploit Available at Github
CVE-2026-0300 has a 7 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-0300.
| URL | Resource |
|---|---|
| https://security.paloaltonetworks.com/CVE-2026-0300 | |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-0300 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-0300
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Python
PAN-OS CVE-2026-0300 Non-Destructive Exposure Survey Tool
cve cve-2026-0300 paloalto paloaltonetworks pan-os
Python
Security Research and Proof-of-Concept (PoC) for CVE-2026-0300 : Unauthenticated Remote Code Execution (RCE) in Palo Alto Networks PAN-OS User-ID Portal.
cve-2026-0300 exploit palo-alto pan-os rce
Python
Read-only audit tooling for CVE-2026-0300 (PAN-OS User-ID Authentication Portal exposure)
Python
CVE-2026-0300
Python
a honeypot for CVE-2026-0300
Python Shell
A research-grade Proof-of-Concept (PoC) for CVE-2026-0300, targeting the Buffer Overflow vulnerability in Palo Alto Networks PAN-OS User-ID™ Authentication Portal (CWE-787).
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-0300 vulnerability anywhere in the article.
-
The Cyber Express
CISA Launches CI Fortify to Defend Critical Infrastructure From Nation-State Cyber Threats
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has launched a new initiative called “CI Fortify” aimed at helping critical infrastructure operators prepare for disruptive cyberattack ... Read more
The following table lists the changes that have been made to the
CVE-2026-0300 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 06, 2026
Action Type Old Value New Value Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300 -
New CVE Received by [email protected]
May. 06, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:C/RE:M/U:Red Added CWE CWE-787 Added Reference https://security.paloaltonetworks.com/CVE-2026-0300