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CVE-2021-29484

Status: ModifiedMedium (6.1)—💥 Exploit

Ghost is a Node.js CMS. An unused endpoint added during the development of 4.0.0 has left sites vulnerable to untrusted users gaining access to Ghost Admin. Attackers can gain access by getting logged in users to click a link containing malicious code. Users do not need to enter credentials and may not know they've visited a malicious site. Ghost(Pro) has already been patched. We can find no evidence that the issue was exploited on Ghost(Pro) prior to the patch being added. Self-hosters are impacted if running Ghost a version between 4.0.0 and 4.3.2.

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Immediate action should be taken to secure your site. The issue has been fixed in 4.3.3, all 4.x sites should upgrade as soon as possible. As the endpoint is unused, the patch simply removes it. As a workaround blocking access to /ghost/preview can also mitigate the issue.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

💥 Public exploits

Exploit code or detection templates are publicly available. This is not the same as confirmed active exploitation (KEV), but it raises the risk: patch with priority.

Affected technologies (1)

Ghost — Ghost

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-29484",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 4.3,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 6.8,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.2,
        "exploitabilityScore": 1.6
      },
      {
        "type": "Secondary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 6.1,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 2.7,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "TryGhost",
          "product": "Ghost",
          "versions": [
            {
              "status": "affected",
              "version": ">= 4.0.0, < 4.3.3"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-04-29T21:15:08.590",
  "references": [
    {
      "url": "https://blog.sonarsource.com/ghost-admin-takeover",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://forum.ghost.org/t/critical-security-update-available-for-ghost-4-x/22290",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/TryGhost/Ghost/security/advisories/GHSA-9fgx-q25h-jxrg",
      "tags": [
        "Mitigation",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://www.npmjs.com/package/ghost",
      "tags": [
        "Product",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://blog.sonarsource.com/ghost-admin-takeover",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://forum.ghost.org/t/critical-security-update-available-for-ghost-4-x/22290",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/TryGhost/Ghost/security/advisories/GHSA-9fgx-q25h-jxrg",
      "tags": [
        "Mitigation",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.npmjs.com/package/ghost",
      "tags": [
        "Product",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Ghost is a Node.js CMS. An unused endpoint added during the development of 4.0.0 has left sites vulnerable to untrusted users gaining access to Ghost Admin. Attackers can gain access by getting logged in users to click a link containing malicious code. Users do not need to enter credentials and may not know they've visited a malicious site. Ghost(Pro) has already been patched. We can find no evidence that the issue was exploited on Ghost(Pro) prior to the patch being added. Self-hosters are impacted if running Ghost a version between 4.0.0 and 4.3.2. Immediate action should be taken to secure your site. The issue has been fixed in 4.3.3, all 4.x sites should upgrade as soon as possible. As the endpoint is unused, the patch simply removes it. As a workaround blocking access to /ghost/preview can also mitigate the issue."
    },
    {
      "lang": "es",
      "value": "Ghost es un CMS Node.js. Un endpoint sin uso agregado durante el desarrollo de la versión 4.0.0 ha dejado los sitios vulnerables a que usuarios no confiables que obtienen acceso a Ghost Admin. Los atacantes pueden conseguir acceso al hacer que unos usuarios que tengan iniciada la sesión hagan clic en un enlace que contenga código malicioso. Los usuarios no necesitan introducir sus credenciales y es posible que no sepan que han visitado un sitio malicioso. Ghost(Pro) ya ha sido parcheado. No hemos encontrado pruebas de que el problema se haya explotado en Ghost(Pro) antes de que se agregara el parche. Los  autohospedadores están afectados si ejecutan Ghost en una versión entre 4.0.0 y 4.3.2. Se deben tomar medidas inmediatas para proteger su sitio. El problema ha sido corregido en 4.3.3, todos los sitios 4.x deberían actualizarse lo antes posible. Como el endpoint sin uso, el parche simplemente lo elimina. Como solución alternativa, bloquear el acceso a /ghost/preview también puede mitigar el problema."
    }
  ],
  "lastModified": "2026-06-17T03:47:44.237",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:ghost:ghost:*:*:*:*:*:node.js:*:*",
              "vulnerable": true,
              "matchCriteriaId": "23DB22EA-9BED-4114-AD2E-CDD95FBA9D42",
              "versionEndExcluding": "4.3.3",
              "versionStartIncluding": "4.0.0"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security-advisories@github.com"
}