Risk Letters

Exploited vulnerability

CVE-2026-0300

TLP:CLEAR

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.

Facts

  • Vendor: Palo Alto Networks
  • Product: PAN-OS
  • CVSS: 9.8
  • EPSS (probability of exploitation within 30 days): 41.7 %
  • On CISA's Known Exploited Vulnerabilities list since: 6 May 2026
  • First known exploitation: 6 May 2026
  • CISA's deadline for US federal agencies: 9 May 2026
  • Weakness: CWE-787
  • First seen by Risk Letters: 6 May 2026

Members see which Nordic sectors the flaw hits, and what to do about it.

Get the full brief

Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD