FKIE_CVE-2021-21391

Vulnerability from fkie_nvd - Published: 2021-04-29 01:15 - Updated: 2026-06-17 03:35
Severity
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Summary
CKEditor 5 provides a WYSIWYG editing solution. This CVE affects the following npm packages: ckeditor5-engine, ckeditor5-font, ckeditor5-image, ckeditor5-list, ckeditor5-markdown-gfm, ckeditor5-media-embed, ckeditor5-paste-from-office, and ckeditor5-widget. Following an internal audit, a regular expression denial of service (ReDoS) vulnerability has been discovered in multiple CKEditor 5 packages. The vulnerability allowed to abuse particular regular expressions, which could cause a significant performance drop resulting in a browser tab freeze. It affects all users using the CKEditor 5 packages listed above at version <= 26.0.0. The problem has been recognized and patched. The fix will be available in version 27.0.0.
References
security-advisories@github.comhttps://github.com/ckeditor/ckeditor5/security/advisories/GHSA-3rh3-wfr4-76mjThird Party Advisory
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-engine
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-font
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-image
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-list
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-media-embed
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-paste-from-office
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-widget
af854a3a-2127-422b-91ae-364da2661108https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-3rh3-wfr4-76mjThird Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-engine
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-font
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-image
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-list
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-media-embed
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-paste-from-office
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-widget
Impacted products
Vendor Product Version
ckeditor ckeditor5-engine *
ckeditor ckeditor5-font *
ckeditor ckeditor5-image *
ckeditor ckeditor5-list *
ckeditor ckeditor5-markdown-gfm *
ckeditor ckeditor5-media-embed *
ckeditor ckeditor5-paste-from-office *
ckeditor ckeditor5-widget *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "ckeditor5",
          "vendor": "ckeditor",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 27.0.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-engine:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "67079ED7-67C7-43E6-B2ED-FC8F38073844",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-font:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "49A57CEA-AF9A-406B-97E3-0174F98CF961",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-image:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "8AA7F807-41B2-492E-AC3F-ECC940A9D087",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-list:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "ECFF8404-52EF-49E0-BB96-5C366362DD9E",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-markdown-gfm:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "2DDE77C4-ECA2-490F-8B67-D9CC0990FF33",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-media-embed:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "C9FD93F0-391D-4910-846C-B972D0737066",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-paste-from-office:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "2B80F6F9-37B6-4FE3-B7C6-07931AD022BD",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5-widget:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "2BD4B908-0A73-4410-813D-34A4108052D0",
              "versionEndExcluding": "27.0.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "CKEditor 5 provides a WYSIWYG editing solution. This CVE affects the following npm packages: ckeditor5-engine, ckeditor5-font, ckeditor5-image, ckeditor5-list, ckeditor5-markdown-gfm, ckeditor5-media-embed, ckeditor5-paste-from-office, and ckeditor5-widget. Following an internal audit, a regular expression denial of service (ReDoS) vulnerability has been discovered in multiple CKEditor 5 packages. The vulnerability allowed to abuse particular regular expressions, which could cause a significant performance drop resulting in a browser tab freeze. It affects all users using the CKEditor 5 packages listed above at version \u003c= 26.0.0. The problem has been recognized and patched. The fix will be available in version 27.0.0."
    },
    {
      "lang": "es",
      "value": "CKEditor 5 proporciona una soluci\u00f3n de edici\u00f3n WYSIWYG.\u0026#xa0;Este CVE afecta a los siguientes paquetes npm: ckeditor5-engine, ckeditor5-font, ckeditor5-image, ckeditor5-list, ckeditor5-markdown-gfm, ckeditor5-media-embed, ckeditor5-paste-from-office y ckeditor5-widget.\u0026#xa0;Despu\u00e9s de una auditor\u00eda interna, se detect\u00f3 una vulnerabilidad de denegaci\u00f3n de servicio de expresi\u00f3n regular (ReDoS) en varios paquetes de CKEditor 5.\u0026#xa0;La vulnerabilidad permiti\u00f3 abusar de determinadas expresiones regulares, lo que podr\u00eda causar una perdida significativa del rendimiento, lo que causar\u00eda la congelaci\u00f3n de la pesta\u00f1a del navegador.\u0026#xa0;Afecta a todos los usuarios que usan los paquetes CKEditor 5 enumerados anteriormente en la versi\u00f3n anterior a 26.0.0 e incluy\u00e9ndola.\u0026#xa0;El problema ha sido reconocido y parcheado.\u0026#xa0;La correcci\u00f3n estar\u00e1 disponible en la versi\u00f3n 27.0.0"
    }
  ],
  "id": "CVE-2021-21391",
  "lastModified": "2026-06-17T03:35:28.500",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 4.3,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-04-29T01:15:07.883",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-3rh3-wfr4-76mj"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-engine"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-font"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-image"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-list"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-media-embed"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-paste-from-office"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-widget"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-3rh3-wfr4-76mj"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-engine"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-font"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-image"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-list"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-media-embed"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-paste-from-office"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-widget"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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