xmldom PI grammar regex ReDoS: quadratic backtracking on unterminated processing instructions

{
  "id": "f95e4f6f82a6c2e3cc72333533244fd6481659ff66952a7ce1f4ef18c48f86ff",
  "url": "https://osv.dev/vulnerability/CVE-2026-83606",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "xmldom PI grammar regex ReDoS: quadratic backtracking on unterminated processing instructions",
    "summary": "xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.0-beta.9 until 0.9.11, the processing-instruction production in lib/grammar.js lets the greedy S+ separator and lazy Char*? data group repeatedly repartition a long whitespace tail when the required closing ?> is absent. Both parsePI and parseProcessingInstruction apply the expression to the entire remaining source, causing quadratic backtracking during DOMParser.parseFromString() under default options and allowing a small unauthenticated XML input to stall the Node.js event loop. This issue is fixed in @xmldom/xmldom version 0.9.11.",
    "evidence": "osv:CVE-2026-83606",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-83606",
      "aliases": [
        "CVE-2026-83606",
        "GHSA-g53g-w8rj-fmg7"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/xmldom/xmldom",
              "type": "GIT",
              "events": [
                {
                  "introduced": "48953f6e6d1d49093c8014c4585b31833de78812"
                },
                {
                  "fixed": "1f0610959ab7b82cc7ad702d1be0243efc5791c0"
                },
                {
                  "fixed": "73df6b8bdbd86f904b9e8c3ab9c49aa54ef2802e"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.9.0-beta.9"
                      },
                      {
                        "fixed": "0.9.11"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "73df6b8bdbd86f904b9e8c3ab9c49aa54ef2802e"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "1f0610959ab7b82cc7ad702d1be0243efc5791c0"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "0.9.11"
                  }
                ]
              }
            }
          ],
          "versions": [
            "0.9.10",
            "0.9.9",
            "0.9.8",
            "0.9.7",
            "0.9.6",
            "0.9.5",
            "0.9.4",
            "0.9.3",
            "0.9.2",
            "0.9.1",
            "0.9.0",
            "0.9.0-beta.11",
            "0.9.0-beta.10",
            "0.9.0-beta.9"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-83606.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.754678838Z",
      "provider": "osv",
      "references": [
        "https://github.com/xmldom/xmldom/releases/tag/0.9.11",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/83xxx/CVE-2026-83606.json",
        "https://github.com/xmldom/xmldom/security/advisories/GHSA-g53g-w8rj-fmg7",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-83606",
        "https://github.com/xmldom/xmldom/commit/73df6b8bdbd86f904b9e8c3ab9c49aa54ef2802e",
        "https://github.com/xmldom/xmldom/pull/1039"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1333",
          "CWE-400"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/83xxx/CVE-2026-83606.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-83606",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491526,
  "published_at": "2026-09-01T14:21:27.215+00:00"
}