HeyForm up to 3.0.0-rc.8 completeSubmission hiddenFields input validation

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.0$0-$5k1.56-

Summaryinfo

A vulnerability classified as critical was found in HeyForm up to 3.0.0-rc.8. This affects an unknown part of the component completeSubmission. The manipulation of the argument hiddenFields results in input validation. This vulnerability is identified as CVE-2026-63428. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical has been found in HeyForm up to 3.0.0-rc.8. Affected is an unknown function of the component completeSubmission. The manipulation of the argument hiddenFields with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-63428 since 07/16/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 3.0.0-rc.9 eliminates this vulnerability.

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Productinfo

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: HeyForm 3.0.0-rc.9

Timelineinfo

07/16/2026 CVE reserved
07/20/2026 +4 days Advisory disclosed
07/20/2026 +0 days VulDB entry created
07/20/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-63428 (🔒)
GCVE (CVE): GCVE-0-2026-63428
GCVE (VulDB): GCVE-100-380646

Entryinfo

Created: 07/20/2026 18:32
Changes: 07/20/2026 18:32 (53)
Complete: 🔍
Cache ID: 216::103

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