SB2026050606 - Buffer overflow in User-ID Authentication Portal on Palo Alto PAN-OS
Published: May 6, 2026
Security Bulletin ID
SB2026050606
CSH Severity
Critical
Patch available
NO
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Out-of-bounds write (CVE-ID: CVE-2026-0300)
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
Cybersecurity Help is not aware of any official remediation provided by the vendor.