markdown-it: Quadratic-time rendering of a single multi-line link reference definition with default options (regression since 14.0)

{
  "id": "6e2a17c9c1c1af101af6909631fb5c7c3a2954791761dc54a921da70a16b482e",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-111758",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "markdown-it: Quadratic-time rendering of a single multi-line link reference definition with default options (regression since 14.0)",
    "summary": "markdown-it is a Markdown parser. From versions 14.1.0 to before 14.3.3, and 15.0.0 to before 15.0.3, a link reference definition whose label or title is never closed is O(n²) with default options. Continuation lines are pulled lazily with str += lineContent in src/rules_block/reference.ts, and the subsequent charCodeAt and slice calls flatten the V8 cons-string, copying everything collected so far; this runs before the rule decides the definition is invalid. No options are required to trigger it. This issue has been patched in versions 14.3.3 and 15.0.3.",
    "evidence": "cve:CVE-2026-111758",
    "products": [
      {
        "name": {
          "value": "markdown-it",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-111758",
      "aliases": [
        "CVE-2026-111758"
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "scope": "UNCHANGED",
            "version": "3.1",
            "baseScore": 7.5,
            "attackVector": "NETWORK",
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "integrityImpact": "NONE",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "availabilityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "confidentialityImpact": "NONE"
          }
        }
      ],
      "affected": [
        {
          "vendor": "markdown-it",
          "product": "markdown-it",
          "versions": [
            {
              "status": "affected",
              "version": ">= 14.1.0, < 14.3.3"
            },
            {
              "status": "affected",
              "version": ">= 15.0.0, < 15.0.3"
            }
          ]
        }
      ],
      "modified": "2026-10-28T16:40:33.483Z",
      "provider": "cve",
      "references": [
        "https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c",
        "https://github.com/markdown-it/markdown-it/commit/48fbc465812c440020c663f040ab22deaf8f1eca",
        "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-2026-111758",
                    "role": "CISA Coordinator",
                    "options": [
                      {
                        "Exploitation": "poc"
                      },
                      {
                        "Automatable": "yes"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "version": "2.0.3",
                    "timestamp": "2026-10-28T16:39:57.942731Z"
                  }
                }
              }
            ],
            "references": [
              {
                "url": "https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c",
                "tags": [
                  "exploit"
                ]
              }
            ],
            "providerMetadata": {
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP",
              "dateUpdated": "2026-10-28T16:40:33.483Z"
            }
          }
        ],
        "cna": {
          "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
          "shortName": "GitHub_M",
          "dateUpdated": "2026-10-20T20:28:40.677Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-111758",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 461057,
  "published_at": "2026-10-20T20:28:40.677+00:00"
}