CVE-2026-42221

{
  "id": "CVE-2026-42221",
  "sourceIdentifier": "[email protected]",
  "published": "2026-05-04T21:16:32.023",
  "lastModified": "2026-10-26T19:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Nginx UI is a web user interface for the Nginx web server. From version 2.0.0 to before version 2.3.8, an unauthenticated network attacker can claim the initial administrator account on a fresh nginx-ui instance during the first-run setup window. The public /api/install endpoint is reachable without authentication, and the request-encryption flow only protects payload confidentiality in transit; it does not authenticate who is allowed to perform installation. A remote attacker who reaches the service before the legitimate operator can set the admin email, username, and password, causing permanent initial-instance takeover. This issue has been patched in version 2.3.8."
    },
    {
      "lang": "es",
      "value": "Nginx UI es una interfaz de usuario web para el servidor web Nginx. Desde la versión 2.0.0 hasta antes de la versión 2.3.8, un atacante de red no autenticado puede reclamar la cuenta de administrador inicial en una instancia nueva de nginx-ui durante la ventana de configuración de la primera ejecución. El endpoint público /api/install es accesible sin autenticación, y el flujo de cifrado de solicitudes solo protege la confidencialidad de la carga útil en tránsito; no autentica quién está autorizado para realizar la instalación. Un atacante remoto que accede al servicio antes que el operador legítimo puede establecer el correo electrónico, nombre de usuario y contraseña del administrador, causando una toma de control permanente de la instancia inicial. Este problema ha sido parcheado en la versión 2.3.8."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "0xJacky",
          "product": "nginx-ui",
          "versions": [
            {
              "version": ">= 2.0.0, < 2.3.8",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.9
      },
      {
        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-05-05T14:06:26.362325Z",
          "id": "CVE-2026-42221",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-306"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:*",
              "versionStartIncluding": "2.0.0",
              "versionEndExcluding": "2.3.8",
              "matchCriteriaId": "623A6AFE-E1C3-4D21-9465-A33CB945AF6F"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8",
      "source": "[email protected]",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    }
  ]
}