CVEvulnerability

CVE-2026-0300

9.3 CRITICAL Known exploited Published 2026-05-06 Modified 2026-10-26 Official page ↗

CISA Known Exploited Vulnerability

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

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.

Added to KEV: 2026-05-06
Remediation due: 2026-05-09
Ransomware use: Unknown
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.
Notes: https://security.paloaltonetworks.com/CVE-2026-0300 ; https://nvd.nist.gov/vuln/detail/CVE-2026-0300

Status: Analyzed
Published: 2026-05-06
Last modified: 2026-10-26
Assigner: [email protected]
CVSS 4.0 ([email protected]): 9.3 CRITICAL — CVSS:4.0/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
CVSS 3.1 ([email protected]): 9.8 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses: CWE-787

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.

Affected configurations

• paloaltonetworks pan-os 10.2.0 • paloaltonetworks pan-os 10.2.1 • paloaltonetworks pan-os 10.2.2 • paloaltonetworks pan-os 10.2.3 • paloaltonetworks pan-os 10.2.4 • paloaltonetworks pan-os 10.2.5 • paloaltonetworks pan-os 10.2.6 • paloaltonetworks pan-os 10.2.7 • paloaltonetworks pan-os 10.2.8 • paloaltonetworks pan-os 10.2.9 • paloaltonetworks pan-os 10.2.10 • paloaltonetworks pan-os 10.2.11 • paloaltonetworks pan-os 10.2.12 • paloaltonetworks pan-os 10.2.13 • paloaltonetworks pan-os 10.2.14 • paloaltonetworks pan-os 10.2.15 • paloaltonetworks pan-os 10.2.16 • paloaltonetworks pan-os 10.2.17 • paloaltonetworks pan-os 10.2.18 • paloaltonetworks pan-os 11.1.0 • paloaltonetworks pan-os 11.1.1 • paloaltonetworks pan-os 11.1.2 • paloaltonetworks pan-os 11.1.3 • paloaltonetworks pan-os 11.1.4 • paloaltonetworks pan-os 11.1.5 • paloaltonetworks pan-os 11.1.6 • paloaltonetworks pan-os 11.1.7 • paloaltonetworks pan-os 11.1.8 • paloaltonetworks pan-os 11.1.9 • paloaltonetworks pan-os 11.1.10 • paloaltonetworks pan-os 11.1.11 • paloaltonetworks pan-os 11.1.12 • paloaltonetworks pan-os 11.1.13 • paloaltonetworks pan-os 11.1.14 • paloaltonetworks pan-os 11.2.0 • paloaltonetworks pan-os 11.2.1 • paloaltonetworks pan-os 11.2.2 • paloaltonetworks pan-os 11.2.3 • paloaltonetworks pan-os 11.2.4 • paloaltonetworks pan-os 11.2.5 • paloaltonetworks pan-os 11.2.6 • paloaltonetworks pan-os 11.2.7 • paloaltonetworks pan-os 11.2.8 • paloaltonetworks pan-os 11.2.9 • paloaltonetworks pan-os 11.2.10 • paloaltonetworks pan-os 11.2.11 • paloaltonetworks pan-os 12.1.2 • paloaltonetworks pan-os 12.1.3 • paloaltonetworks pan-os 12.1.4 • paloaltonetworks pan-os 12.1.5 • paloaltonetworks pan-os 12.1.6 • siemens ruggedcom ape1808 firmware

Weakness · CWE (1)

CWE-787 Out-of-bounds Write weakness

References