Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net

{
  "id": "6e132860a1a3db03ca795779863bf29449c500ba7007fe12b87202ea847f45ce",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-78661",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net",
    "summary": "When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode's Data via string concatenation (n.Data += text) reallocated and copied the accumulated string on every token. Inputs containing many short text runs separated by ignored end tags (such as \"a\") caused O(n^2) allocations and byte copies. Accumulate coalesced text in per-node byte slices during parsing and materialize Data strings once at the end of parse.",
    "evidence": "cve:CVE-2026-78661",
    "products": [
      {
        "name": {
          "value": "golang.org/x/net/html",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-78661",
      "aliases": [
        "CVE-2026-78661"
      ],
      "metrics": [],
      "affected": [
        {
          "vendor": "golang.org/x/net",
          "product": "golang.org/x/net/html",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "0.62.0",
              "versionType": "semver"
            }
          ],
          "packageName": "golang.org/x/net/html",
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "parser.addText"
            },
            {
              "name": "parser.fosterParent"
            },
            {
              "name": "parser.parse"
            },
            {
              "name": "Parse"
            },
            {
              "name": "ParseFragment"
            },
            {
              "name": "ParseFragmentWithOptions"
            },
            {
              "name": "ParseWithOptions"
            }
          ]
        }
      ],
      "modified": "2026-10-27T21:38:56.517Z",
      "provider": "cve",
      "references": [
        "https://go.dev/cl/849365",
        "https://go.dev/issue/82224",
        "https://groups.google.com/g/golang-announce/c/sqrs2vTx_Xs",
        "https://pkg.go.dev/vuln/GO-2026-6860"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
          "shortName": "Go",
          "dateUpdated": "2026-10-27T21:38:56.517Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-78661",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 400613,
  "published_at": "2026-10-27T21:38:56.517+00:00"
}