{
  "id": "CVE-2026-0300",
  "url": "https://spydr.io/cve/CVE-2026-0300",
  "published": "2026-05-06T19:16:35.730Z",
  "modified": "2026-06-17T10:10:43.073Z",
  "score": 9.3,
  "severity": "critical",
  "cvss_version": "4.0",
  "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:C/RE:M/U:Red",
  "score_source": "paloaltonetworks.com",
  "epss": 0.31725,
  "epss_percentile": 0.98252,
  "exploited": true,
  "kev": {
    "added": "2026-05-06",
    "due": "2026-05-09",
    "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.",
    "ransomware": "Unknown",
    "name": "Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability",
    "notes": "https://security.paloaltonetworks.com/CVE-2026-0300 ; https://nvd.nist.gov/vuln/detail/CVE-2026-0300"
  },
  "ssvc_exploitation": "active",
  "vendors": [
    "Palo Alto Networks",
    "Siemens"
  ],
  "products": [
    "Palo Alto Networks Cloud NGFW",
    "Palo Alto Networks PAN-OS",
    "Palo Alto Networks Prisma Access",
    "Siemens RUGGEDCOM APE1808"
  ],
  "cwes": [
    "CWE-787"
  ],
  "description": "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.",
  "status": "Analyzed",
  "score_type": "Secondary",
  "scores": {
    "cvss_v40": 9.3,
    "cvss_v31": 9.8,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://security.paloaltonetworks.com/CVE-2026-0300",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-967325.html",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300",
      "tags": [
        "US Government Resource"
      ]
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-0300",
  "covered_in": [],
  "attribution": [
    {
      "source": "NVD",
      "url": "https://nvd.nist.gov",
      "notice": "This product uses data from the NVD API but is not endorsed or certified by the NVD."
    },
    {
      "source": "CISA KEV",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "notice": "Known exploited vulnerabilities from the CISA KEV catalog."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss",
      "notice": "Exploit prediction scores from FIRST EPSS."
    }
  ]
}