What is CVE-2026-63428?

CVE-2026-63428 is a medium-severity vulnerability in Heyform, classified under Improper Input Validation. CVSS score: 5.8/10. Published 2026-07-20.

How severe is CVE-2026-63428?

Medium severity. CVSS v3 base score is 5.8 out of 10.

Improper input validation in Heyform

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 su…

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N.

Affected products

Heyform — versions < 3.0.0-rc.9

Weakness classification (CWE)

CWE-20 — Improper Input Validation
CWE-915 — Improperly Controlled Modification of Dynamically-Determined Object Attributes

References

security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-63428?: CVE-2026-63428 is a medium-severity vulnerability in Heyform, classified under Improper Input Validation. CVSS score: 5.8/10. Published 2026-07-20.
How severe is CVE-2026-63428?: Medium severity. CVSS v3 base score is 5.8 out of 10.