CVE-2026-63429: Heyform

High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Heyform Heyform: before 3.0.0-rc.9 (fixed in 3.0.0-rc.9)

Published 2026-07-20. Last modified 2026-07-22.