{"id":"CVE-2026-63428","state":"PUBLISHED","title":"HeyForm: completeSubmission persists submitter-supplied hidden fields verbatim without validating against the form's declared hidden-field set","description":"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.","publishedAt":"2026-07-20T15:50:14.065Z","updatedAt":"2026-07-20T16:13:26.732Z","severity":{"score":5.8,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["heyform heyform"],"affected":[{"vendor":"heyform","product":"heyform","versions":[{"version":"< 3.0.0-rc.9","status":"affected"}]}],"references":["https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3","https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2"],"weaknesses":["CWE-20","CWE-915"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63428.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63428","state":"PUBLISHED","datePublished":"2026-07-20T15:50:14.065Z","dateUpdated":"2026-07-20T16:13:26.732Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-16T19:35:57.766Z"},"containers":{"cna":{"title":"HeyForm: completeSubmission persists submitter-supplied hidden fields verbatim without validating against the form's declared hidden-field set","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"heyform","product":"heyform","versions":[{"version":"< 3.0.0-rc.9","status":"affected"}]}],"references":[{"url":"https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3","name":"https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2","name":"https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.8,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","description":"CWE-20: Improper Input Validation","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-915","lang":"en","description":"CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-20T15:50:14.065Z"},"source":{"advisory":"GHSA-r7vg-xh87-v4w3","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-20T16:11:40.127768Z","id":"CVE-2026-63428","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-20T16:13:26.732Z"}}]}}}