{
  "id": "CVE-2023-33009",
  "url": "https://spydr.io/cve/CVE-2023-33009",
  "published": "2023-05-24T13:15:09.560Z",
  "modified": "2026-06-17T06:00:16.810Z",
  "score": 9.8,
  "severity": "critical",
  "cvss_version": "3.1",
  "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
  "score_source": "zyxel.com.tw",
  "epss": 0.28144,
  "epss_percentile": 0.98065,
  "exploited": true,
  "kev": {
    "added": "2023-06-05",
    "due": "2023-06-26",
    "action": "Apply updates per vendor instructions.",
    "ransomware": "Unknown",
    "name": "Zyxel Multiple Firewalls Buffer Overflow Vulnerability",
    "notes": "https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls; https://nvd.nist.gov/vuln/detail/CVE-2023-33009"
  },
  "ssvc_exploitation": "active",
  "vendors": [
    "Zyxel"
  ],
  "products": [
    "Zyxel ATP series firmware",
    "Zyxel USG FLEX series firmware",
    "Zyxel USG FLEX 50(W) firmware",
    "Zyxel USG20(W)-VPN firmware",
    "Zyxel VPN series firmware",
    "Zyxel ZyWALL/USG series firmware"
  ],
  "cwes": [
    "CWE-120"
  ],
  "description": "A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX series firmware versions 4.60 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.60 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.60 through 5.36 Patch 1, VPN series firmware versions 4.60 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.60 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.",
  "status": "Analyzed",
  "score_type": "Secondary",
  "scores": {
    "cvss_v40": null,
    "cvss_v31": 9.8,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls",
      "tags": [
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-33009",
      "tags": [
        "US Government Resource"
      ]
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2023-33009",
  "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."
    }
  ]
}