Trix: Stored XSS via HTMLParser attribute injection on paste

{
  "id": "b1c284dcffdbf0acf3a445de65478e277a9a3ef158b5a60486d6588ca8435bc5",
  "url": "https://osv.dev/vulnerability/CVE-2026-73428",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Trix: Stored XSS via HTMLParser attribute injection on paste",
    "summary": "Trix is a what-you-see-is-what-you-get rich text editor for everyday writing. Prior to 2.1.18, Trix is vulnerable to stored cross-site scripting when crafted HTML is pasted into the editor. HTMLParser processes a mock attachment in a `` with an empty `data-trix-attachment=\"{}\"` value, causing data-trix-attributes to be applied to a plain string piece. StringPiece.fromJSON accepts an unvalidated href, allowing a javascript: URI to enter the document model and serialized HTML and execute when another user renders and clicks the content. Applications that apply server-side HTML sanitization can neutralize the payload on save. This issue is fixed in version 2.1.18.",
    "evidence": "osv:CVE-2026-73428",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-73428",
      "aliases": [
        "CVE-2026-73428",
        "GHSA-53g2-mvcc-q9x3"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/basecamp/trix",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "da8869922e19bc3f852091468d34029af80813e7"
                },
                {
                  "fixed": "9c0a993d9fc2ffe9d56b013b030bc238f9c0557c"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.1.18"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "9c0a993d9fc2ffe9d56b013b030bc238f9c0557c"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "da8869922e19bc3f852091468d34029af80813e7"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.1.18"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.1.17",
            "v2.1.16",
            "v2.1.15",
            "v2.1.14",
            "v2.1.13",
            "v2.1.12",
            "v2.1.11",
            "v2.1.10",
            "v2.1.9",
            "v2.1.8",
            "v2.1.7",
            "v2.1.6",
            "v2.1.5",
            "v2.1.4",
            "2.1.3",
            "v2.1.1",
            "1.3.1",
            "v2.1.0",
            "v2.0.10",
            "v2.0.9",
            "v2.0.8",
            "v2.0.7",
            "v2.0.6",
            "v2.0.5",
            "v2.0.4",
            "v2.0.3",
            "v2.0.2",
            "v2.0.1",
            "1.3.0",
            "1.2.4",
            "1.2.3",
            "1.2.2",
            "1.2.1",
            "1.2.0",
            "1.1.1",
            "1.1.0",
            "1.0.0",
            "0.12.1",
            "0.12.0",
            "0.11.4",
            "0.11.3",
            "0.11.2",
            "0.11.1",
            "0.11.0",
            "0.10.2",
            "0.10.1",
            "0.10.0",
            "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",
            "0.8.0",
            "0.5.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73428.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:53.338225815Z",
      "provider": "osv",
      "references": [
        "https://github.com/basecamp/trix/releases/tag/v2.1.18",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73428.json",
        "https://github.com/basecamp/trix/security/advisories/GHSA-53g2-mvcc-q9x3",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-73428",
        "https://github.com/basecamp/trix/commit/9c0a993d9fc2ffe9d56b013b030bc238f9c0557c",
        "https://github.com/basecamp/trix/pull/1293"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73428.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-73428",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 522223,
  "published_at": "2026-08-13T22:04:19.121+00:00"
}