{"id":"CVE-2026-63428","summary":"HeyForm: completeSubmission persists submitter-supplied hidden fields verbatim without validating against the form's declared hidden-field set","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.","aliases":["GHSA-r7vg-xh87-v4w3"],"modified":"2026-07-22T05:32:31.198175509Z","published":"2026-07-20T15:50:14.065Z","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"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63428.json"},{"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"},{"type":"FIX","url":"https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/heyform/heyform","events":[{"introduced":"0"},{"fixed":"092e255e9e02565de1b3c057f3dad849160952d2"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"3.0.0-rc.9"}]}}],"versions":["v3.0.0-rc.8","v3.0.0-rc.7","v3.0.0-rc.6","v3.0.0-rc.5","v3.0.0-rc.4","v3.0.0-rc.3","v3.0.0-rc.2","v3.0.0-rc.1","v3.0.0-alpha.3","v3.0.0-alpha-2","v0.1.0","v0.0.17","v0.0.16","v0.0.15","v0.0.13","v0.0.12","v0.0.11","v0.0.10","v0.0.9","v0.0.8","v0.0.7","v0.0.6","v0.0.5","v0.0.4","v0.0.3","v0.0.2","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63428.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"}]}