CVE-2026-0300 — Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
2026-05-06 • CISA Known Exploited Vulnerability
[event] 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.
> AFFECTED SOFTWARE
| Field | Value |
|---|---|
| Vendor | Palo Alto Networks |
| Product | PAN-OS |
| CWE | CWE-787 |
| CVE ID | CVE-2026-0300 |
| Date Added | 2026-05-06 |
| Due Date | 2026-05-09 |
| Ransomware Campaign | Unknown |
> MITIGATION
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.
Due Date: 2026-05-09