CVE-2026-0300
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
Exploited in the wild
This vulnerability is on the CISA Known Exploited Vulnerabilities list, added 2026-05-06. Federal due date: 2026-05-09.
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.
Impact
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 products
| Vendor | Product | Affected versions |
|---|---|---|
| Paloaltonetworks | Pan-Os | Versions 10.2.0, 10.2.1, 10.2.2, 10.2.3, 10.2.4, 10.2.5 |
| Siemens | Ruggedcom Ape1808 Firmware | All versions |