CVE-2026-0300 — Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
Overview
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.
Vulnerability details
- CVE ID
- CVE-2026-0300
- Vulnerability
- Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
- Vendor
- Palo Alto Networks
- Affected products
- Palo Alto Networks: PAN-OS
- Severity
- HIGH
- Exploitation status
- Actively exploited in the wild (CISA KEV)
- EPSS score
- 31.8% probability of exploitation in 30 days · 98th percentile
- Published
- 2026-05-06
Remediation guidance
CVE-2026-0300 is in CISA's Known Exploited Vulnerabilities (KEV) catalog — U.S. federal civilian agencies are required to remediate it under Binding Operational Directive 22-01. Treat it as a priority for every environment.
Apply the vendor's official security update for Palo Alto Networks the affected product as soon as possible. Where a patch is unavailable, apply vendor mitigations or isolate/segment exposed systems.
FIRST EPSS estimates a 31.8% probability that CVE-2026-0300 will be exploited within the next 30 days (98th percentile of all CVEs) — useful for risk-based patch sequencing.
Hunt for indicators of compromise tied to this vulnerability and confirm logging/EDR coverage on affected assets.
Authoritative references
Remediate CVE-2026-0300 — and stay ahead of the next one
CVE-2026-0300 is listed in the CISA KEV catalog as actively exploited — treat remediation as urgent. Scan your domain free to see whether CVE-2026-0300 and other Palo Alto Networks issues affect you and get a prioritized remediation report (full report from ₹999) — or stream the full feed of 1,600+ actively-exploited CVEs straight into your SOC.
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