CVE-2026-63429

High

Description

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.

SeverityHigh

CVSS8.6

Exploit probability—

ProductHeyform

PublishedJul 20, 2026

First seenJul 20, 2026

Weakness typeCWE-306Missing authentication for critical function CWE-434Unrestricted upload of dangerous file type

How to fix

Sources list no fixed version or patch link for this vulnerability.

Affected products

Product	Affected versions	Fixed in
heyform heyform	< 3.0.0-rc.9	—

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.