CVE intelligence and bounded remediation

CVE-2026-0300 — Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

Critical CVSS 9.8 CISA KEV

A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets. The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses. Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.

Severity
Critical
CVSS
9.8 (3.1)
Published
2026-05-06
CISA KEV
Known exploited
Ecosystem
operating-system
Weaknesses
CWE-787

Affected products

  • paloaltonetworks / pan-os / 10.2.0
  • paloaltonetworks / pan-os / 10.2.1
  • paloaltonetworks / pan-os / 10.2.2
  • paloaltonetworks / pan-os / 10.2.3
  • paloaltonetworks / pan-os / 10.2.4
  • paloaltonetworks / pan-os / 10.2.5

Showing 6 representative product identities from 163 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

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Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

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