Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
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.
What to do
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.
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Details
- Vendor
- Palo Alto Networks
- Product
- PAN-OS
- CVE
- CVE-2026-0300
- Affected versions
- PAN-OS 12.1: from 12.1.0 to 12.1.7 (excluded) — fixed in 12.1.7
PAN-OS 11.2: from 11.2.0 to 11.2.12 (excluded) — fixed in 11.2.12
PAN-OS 11.1: from 11.1.0 to 11.1.15 (excluded) — fixed in 11.1.15
PAN-OS 10.2: from 10.2.0 to 10.2.18-h6 (excluded) — fixed in 10.2.18-h6 (from the advisory and NVD; check the exact builds in the official advisory) - CVSS score
- 9.8
- Actively exploited
- Yes, listed in the CISA Known Exploited Vulnerabilities catalog
- CISA due date
- May 9, 2026 (deadline for US federal agencies: a good benchmark for you too)
- Source
- CISA KEV – original advisory
- Published
- May 6, 2026
The description and the recommended action are quoted from the public advisory; severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.