markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled

{
  "id": "d6aa2e3f77a33d7226db166ad0828685d37d040e23a302eecceb6da7e50fd3db",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-111766",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled",
    "summary": "markdown-it is a Markdown parser. Prior to 14.3.3 and 15.0.3, when the html option or commonmark preset is enabled and the constructs occur inside a paragraph, attacker-controlled Markdown containing repeated unterminated inline HTML comments, processing instructions, declarations, or CDATA sections reaches src/rules_inline/html_inline.ts. Its HTML_TAG_RE match searches the remaining suffix for the appropriate terminator; when no terminator is present, parsing advances to the next opener and repeats the match over overlapping input, causing quadratic processing and denial of service through event-loop blocking or an unresponsive browser main thread. HTML blocks and the default HTML-disabled configuration are not affected by these payloads. This issue is fixed in versions 14.3.3 and 15.0.3.",
    "evidence": "cve:CVE-2026-111766",
    "products": [
      {
        "name": {
          "value": "markdown-it",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-111766",
      "aliases": [
        "CVE-2026-111766"
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "scope": "UNCHANGED",
            "version": "3.1",
            "baseScore": 3.7,
            "attackVector": "NETWORK",
            "baseSeverity": "LOW",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "integrityImpact": "NONE",
            "userInteraction": "NONE",
            "attackComplexity": "HIGH",
            "availabilityImpact": "LOW",
            "privilegesRequired": "NONE",
            "confidentialityImpact": "NONE"
          }
        }
      ],
      "affected": [
        {
          "vendor": "markdown-it",
          "product": "markdown-it",
          "versions": [
            {
              "status": "affected",
              "version": ">= 15.0.0, < 15.0.3"
            },
            {
              "status": "affected",
              "version": "< 14.3.3"
            }
          ]
        }
      ],
      "modified": "2026-10-26T17:37:11.818Z",
      "provider": "cve",
      "references": [
        "https://github.com/markdown-it/markdown-it/security/advisories/GHSA-vfgh-jcmw-g37q",
        "https://github.com/markdown-it/markdown-it/commit/928bc8c11ded60181c0e7fc5aa954eec582e8e79",
        "https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503",
        "https://github.com/markdown-it/markdown-it/releases/tag/14.3.3",
        "https://github.com/markdown-it/markdown-it/releases/tag/15.0.3"
      ],
      "provider_metadata": {
        "adp": [
          {
            "title": "CISA ADP Vulnrichment",
            "metrics": [
              {
                "other": {
                  "type": "ssvc",
                  "content": {
                    "id": "CVE-2026-111766",
                    "role": "CISA Coordinator",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "version": "2.0.3",
                    "timestamp": "2026-10-26T17:29:30.362422Z"
                  }
                }
              }
            ],
            "providerMetadata": {
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP",
              "dateUpdated": "2026-10-26T17:37:11.818Z"
            }
          }
        ],
        "cna": {
          "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
          "shortName": "GitHub_M",
          "dateUpdated": "2026-10-19T19:47:46.488Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-111766",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 326366,
  "published_at": "2026-10-19T19:47:46.488+00:00"
}