CVE-2026-63428

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.

• CWE-20
• CWE-915

• https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2
• https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3
• https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3

Published

Jul 20, 2026

Last Modified

Jul 22, 2026

Status

Deferred

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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