{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "3.0.0-rc.9"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "84d8c9993ae1c89b9a9e4793dac4331a26b12ba3"
            }
          ],
          "repo": "https://github.com/heyform/heyform",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-r7vg-xh87-v4w3"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-20",
      "CWE-915"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63428.json"
  },
  "details": "HeyForm is an open-source form builder. Prior to version 3.0.0-rc.9, `completeSubmission` accepts a `hiddenFields: [{id, name, value}]` array from the submitter and stores it verbatim in `submission.hiddenFields`, without validating the supplied `id`/`name` against the form's declared `form.hiddenFields` schema. An anonymous form submitter can therefore inject arbitrary key/value pairs (including XSS payloads, fake authorization metadata, integration-relevant values) into the stored submission. These fields are subsequently forwarded as-is to every webhook integration registered on the form. Version 3.0.0-rc.9 contains a patch for the issue.",
  "id": "CVE-2026-63428",
  "modified": "2026-07-21T03:42:16.021250766Z",
  "published": "2026-07-20T15:50:14.065Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63428.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63428"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "HeyForm: completeSubmission persists submitter-supplied hidden fields verbatim without validating against the form's declared hidden-field set"
}