CVE-2026-0300 — Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
CVE-2026-0300: Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
CISA Known Exploited Vulnerability (KEV)
| Vendor / project | Palo Alto Networks |
| Product | PAN-OS |
| Date added | 2026-05-06 |
| Due date | 2026-05-09 |
| Ransomware campaign use | Unknown |
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 (CISA)
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
References
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-0300
- KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog