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GHSA-75PG-WVH3-34JR

Vulnerability from github – Published: 2026-10-28 00:30 – Updated: 2026-10-28 00:30

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-78661"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-27T22:18:05Z",
    "severity": null
  },
  "details": "When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode\u0027s 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\u003c/x\u003e\") 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.",
  "id": "GHSA-75pg-wvh3-34jr",
  "modified": "2026-10-28T00:30:30Z",
  "published": "2026-10-28T00:30:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78661"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/cl/849365"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/issue/82224"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/golang-announce/c/sqrs2vTx_Xs"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-6860"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-78661 (GCVE-0-2026-78661)

Vulnerability from cvelistv5 – Published: 2026-10-27 21:38 – Updated: 2026-10-27 21:38

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</x>") 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.

Severity

No CVSS data available.

CWE

CWE-407 - Inefficient Algorithmic Complexity

Assigner

Go CNA under the Google root

CNA scorecard E 42/100 over 76 records in the last 180 days details

References

4 references

URL	Tags
https://go.dev/cl/849365
https://go.dev/issue/82224
https://groups.google.com/g/golang-announce/c/sqr…
https://pkg.go.dev/vuln/GO-2026-6860

Impacted products

1 product

Vendor	Product	Version
golang.org/x/net	golang.org/x/net/html	Affected: 0 , < 0.62.0 (semver)

Credits

Markus Magnuson

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "golang.org/x/net/html",
          "product": "golang.org/x/net/html",
          "programRoutines": [
            {
              "name": "parser.addText"
            },
            {
              "name": "parser.fosterParent"
            },
            {
              "name": "parser.parse"
            },
            {
              "name": "Parse"
            },
            {
              "name": "ParseFragment"
            },
            {
              "name": "ParseFragmentWithOptions"
            },
            {
              "name": "ParseWithOptions"
            }
          ],
          "vendor": "golang.org/x/net",
          "versions": [
            {
              "lessThan": "0.62.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Markus Magnuson"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode\u0027s 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\u003c/x\u003e\") 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."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-407: Inefficient Algorithmic Complexity",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-27T21:38:56.517Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/cl/849365"
        },
        {
          "url": "https://go.dev/issue/82224"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/sqrs2vTx_Xs"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-6860"
        }
      ],
      "title": "Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-78661",
    "datePublished": "2026-10-27T21:38:56.517Z",
    "dateReserved": "2026-08-24T23:36:15.738Z",
    "dateUpdated": "2026-10-27T21:38:56.517Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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