HeyForm up to 3.0.0 File Upload /api/upload cross-domain policy

Summaryinfo

A vulnerability described as problematic has been identified in HeyForm up to 3.0.0. This impacts an unknown function of the file /api/upload of the component File Upload. Executing a manipulation can lead to cross-domain policy. This vulnerability is handled as CVE-2026-102615. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in HeyForm up to 3.0.0. This vulnerability affects an unknown code block of the file /api/upload of the component File Upload. The manipulation with an unknown input leads to a cross-domain policy vulnerability. The CWE definition for the vulnerability is CWE-942. The product uses a cross-domain policy file that includes domains that should not be trusted. As an impact it is known to affect confidentiality. CVE summarizes:

HeyForm is an open-source form builder. Prior to 3.0.1, /api/upload accepts a file according to the client-controlled multipart file.mimetype while retaining an HTML filename, and static/upload serves the resulting file as text/html with contentSecurityPolicy: false. An ordinary user can therefore upload active HTML that executes on the HeyForm origin when a victim opens its returned URL. The same-origin script can access /graphql with the victim's session and read or modify data available to that account. The code also permits upload requests tied to an active public form through formId, openToken, and a fieldId belonging to a file or signature question, although the advisory did not fully verify that unauthenticated path end to end. This issue is fixed in version 3.0.1.

The advisory is available at github.com. This vulnerability was named CVE-2026-102615 since 09/29/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 3.0.1 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

• HeyForm

Version

• 3.0

Website

• Product: https://github.com/heyform/heyform/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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