CVE-2026-63428 Details
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.
A vulnerability exists in HeyForm, an open-source form builder, in versions prior to 3.0.0-rc.9. The issue arises in the `completeSubmission` mutation, which accepts a `hiddenFields` array from the submitter. This array is stored verbatim in the submission data without validating the `id` or `name` against the form's schema. As a result, an anonymous submitter can inject arbitrary key/value pairs, including XSS payloads, fake authorization data, and other integration-relevant values. These injected fields are then forwarded as-is to every webhook integration associated with the form.
Users can update to HeyForm version 3.0.0-rc.9 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 20, 2026CISA-ADP
Assessed Jul 20, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3 | CISA-ADP | AdvisoryExploitTechnical AnalysisVendor |
| https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2 | [email protected] | Source CodeVendor |
| https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3 | [email protected] | AdvisoryExploitTechnical AnalysisVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-20 | Improper Input Validation | [email protected] |
| CWE-915 | Improperly Controlled Modification of Dynamically-Determined Object Attributes | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| HeyForm | <= 3.0.0-rc.8 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 20, 2026 | CVE Modified | CISA-ADP |
| Jul 20, 2026 | New CVE Received | [email protected] |