CVE-2026-0300

Palo Alto Networks PAN-OSActively Exploited (CISA KEV)CVSS 9.3KEV0-Day

Actively exploited (CISA KEV) - patch before 2026-05-09

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.

Actively exploited in the wild and listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No distribution fix is listed yet; apply vendor mitigations and monitor.

Recommended action: No fix is published yet for an actively-exploited flaw. Apply vendor mitigations, restrict exposure, and watch for a patch.

CVE-2026-0300 Palo Alto Networks PAN-OS Actively Exploited (CISA KEV)

Severity metrics

CVSS 4.0 : 9.3 CRITICAL · CVSS 3.1 : 9.8 CRITICAL

Attack vectorNetwork (remote)

Attack complexityLow

Attack requirementsNone

Privileges requiredNone

User interactionNone

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Subsequent confidentialityLow

Subsequent integrityLow

Subsequent availabilityNone

Vector: AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/AU:Y/R:U/V:C/RE:M/U:Red

Affected & fixed versions by distribution

Versions are the native distribution strings (backport-aware): RHEL/Debian/SUSE backport fixes, so compare with the distro version comparator (dpkg / rpm / vercmp), not the upstream version.

No affected package in the tracked watchlist yet (Debian, Ubuntu, Arch, SUSE, Red Hat...). Triage may still be pending.

Sources

Advisory NVD CVE.org

Published 2026-07-04