Vulnerability 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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952
- https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3
- https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3
FAQ
What is CVE-2026-63428?
CVE-2026-63428 is a vulnerability with a CVSS score of 5.8 (MEDIUM). 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.h...
How severe is CVE-2026-63428?
CVE-2026-63428 has been rated MEDIUM with a CVSS base score of 5.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-63428?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.