CVE record
CVE-2026-0300
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
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.
CVE evidence
Known exploitation
Listed in CISA KEV
Absence from the fetched catalog does not establish that exploitation has not occurred.
Severity
unknown
No parseable CVSS vector returned
Affected packages
0
Supported package records returned by OSV. Vendor and product names are not used to infer matches.
CISA Known Exploited Vulnerabilities
Catalog record
- Vendor / project
- Palo Alto Networks
- Product
- PAN-OS
- Date added
- May 6, 2026
- CISA federal remediation due date
- May 9, 2026
- Required action
- 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.
- Known ransomware campaign use
- Unknown
- CWE
- CWE-787
OSV package mapping
Affected open-source packages
OSV did not return a package mapping in the five supported ecosystems. RequestGuard does not infer package names from the CISA vendor or product fields.