SB2026050606 - Buffer overflow in User-ID Authentication Portal on Palo Alto PAN-OS

CSH
CYBERSECURITY HELP
Sign In REGISTER

Main Vulnerability Database SB2026050606

SB2026050606 - Buffer overflow in User-ID Authentication Portal on Palo Alto PAN-OS

Published: May 6, 2026 Updated: May 22, 2026

Security Bulletin ID SB2026050606
CSH Severity
Critical
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Code execution

Breakdown by Severity

Critical 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Out-of-bounds write (CVE-ID: CVE-2026-0300)

CWE-ID: CWE-787 - Out-of-bounds write

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/U:Red


The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a boundary error within the User-ID Authentication Portal (aka Captive Portal) service. A remote attacker can send specially crafted packets to the device, trigger an out-of-bounds write and execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls.

Note, the vulnerability is being actively exploited in the wild.


Remediation

Install update from vendor's website.

References