HeyForm up to 3.0.0-rc.8 /api/upload unrestricted upload

Summaryinfo

A vulnerability described as critical has been identified in HeyForm up to 3.0.0-rc.8. Affected by this vulnerability is an unknown functionality of the file /api/upload. Executing a manipulation can lead to unrestricted upload. The identification of this vulnerability is CVE-2026-63429. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in HeyForm up to 3.0.0-rc.8. It has been declared as critical. This vulnerability affects an unknown code block of the file /api/upload. The manipulation with an unknown input leads to a unrestricted upload vulnerability. The CWE definition for the vulnerability is CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

HeyForm is an open-source form builder. Prior to version 3.0.0-rc.9, `POST /api/upload` has no authentication guard, no global guard, no form-context validation, no `openToken` requirement, and no session cookie check. Any anonymous internet user can upload files (PDF, DOC/DOCX, XLS/XLSX, CSV, TXT, MP4, images, etc., up to 10 MB) and receive a permanent public URL on the HeyForm domain. The endpoint is used by both authenticated form creators and unauthenticated form submitters; because no form-context binding exists, every request to it is anonymously accepted. Version 3.0.0-rc.9 contains a patch for the issue.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-63429 since 07/16/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1608.002.

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

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-45986). Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• HeyForm

Version

• 3.0.0-rc.0
• 3.0.0-rc.1
• 3.0.0-rc.2
• 3.0.0-rc.3
• 3.0.0-rc.4
• 3.0.0-rc.5
• 3.0.0-rc.6
• 3.0.0-rc.7
• 3.0.0-rc.8

Website

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

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Once again VulDB remains the best source for vulnerability data.

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