FKIE_CVE-2021-21254

Vulnerability from fkie_nvd - Published: 2021-01-29 22:15 - Updated: 2026-06-17 03:35
Severity
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
CKEditor 5 is an open source rich text editor framework with a modular architecture. The CKEditor 5 Markdown plugin (@ckeditor/ckeditor5-markdown-gfm) before version 25.0.0 has a regex denial of service (ReDoS) vulnerability. The vulnerability allowed to abuse link recognition regular expression, which could cause a significant performance drop resulting in browser tab freeze. It affects all users using CKEditor 5 Markdown plugin at version <= 24.0.0. The problem has been recognized and patched. The fix will be available in version 25.0.0.
References
security-advisories@github.comhttps://github.com/ckeditor/ckeditor5/releases/tag/v25.0.0Release Notes, Third Party Advisory
security-advisories@github.comhttps://github.com/ckeditor/ckeditor5/security/advisories/GHSA-hgmg-hhc8-g5wrThird Party Advisory
security-advisories@github.comhttps://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm
af854a3a-2127-422b-91ae-364da2661108https://github.com/ckeditor/ckeditor5/releases/tag/v25.0.0Release Notes, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-hgmg-hhc8-g5wrThird Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm
Impacted products
Vendor Product Version
ckeditor ckeditor5 *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "ckeditor5",
          "vendor": "ckeditor",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 25.0.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:ckeditor:ckeditor5:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "8B47943C-76FE-4852-86F0-14CA6F0BD30D",
              "versionEndExcluding": "25.0.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "CKEditor 5 is an open source rich text editor framework with a modular architecture. The CKEditor 5 Markdown plugin (@ckeditor/ckeditor5-markdown-gfm) before version 25.0.0 has a regex denial of service (ReDoS) vulnerability. The vulnerability allowed to abuse link recognition regular expression, which could cause a significant performance drop resulting in browser tab freeze. It affects all users using CKEditor 5 Markdown plugin at version \u003c= 24.0.0. The problem has been recognized and patched. The fix will be available in version 25.0.0."
    },
    {
      "lang": "es",
      "value": "CKEditor 5 es un framework de edici\u00f3n de texto enriquecido de c\u00f3digo abierto con una arquitectura modular.\u0026#xa0;El plugin CKEditor 5 Markdown (@ckeditor/ckeditor5-markdown-gfm) anterior a versi\u00f3n 25.0.0, presenta una vulnerabilidad de denegaci\u00f3n de servicio de expresiones regulares  (ReDoS).\u0026#xa0;La vulnerabilidad permiti\u00f3 abusar de la expresi\u00f3n regular de reconocimiento de enlace, lo que podr\u00eda causar una ca\u00edda significativa en el rendimiento resultando en la congelaci\u00f3n de la pesta\u00f1a del navegador.\u0026#xa0;Afecta a todos los usuarios que usan el plugin CKEditor 5 Markdown en la versi\u00f3n anterior a 24.0.0 e incluy\u00e9ndola.\u0026#xa0;El problema ha sido reconocido y parcheado.\u0026#xa0;La correcci\u00f3n estar\u00e1 disponible en la versi\u00f3n 25.0.0"
    }
  ],
  "id": "CVE-2021-21254",
  "lastModified": "2026-06-17T03:35:08.190",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "NETWORK",
          "authentication": "SINGLE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 4.0,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:L/Au:S/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 8.0,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-01-29T22:15:14.797",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes",
        "Third Party Advisory"
      ],
      "url": "https://github.com/ckeditor/ckeditor5/releases/tag/v25.0.0"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-hgmg-hhc8-g5wr"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Release Notes",
        "Third Party Advisory"
      ],
      "url": "https://github.com/ckeditor/ckeditor5/releases/tag/v25.0.0"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-hgmg-hhc8-g5wr"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm"
    }
  ],
  "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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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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