CVE-2026-0300
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
CVSS
—
No CVSS
EPSS
31.7%
p98
KEV
YES
May 6, 2026
Exploit Today
79
0-100
Published: — · Last modified: —
Product
Palo Alto Networks / PAN-OS
Vulnerability
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
Added to KEV
May 6, 2026
Remediate by
May 9, 2026
Known ransomware use
No
Summary description
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.
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