CVE-2026-63429 HeyForm has unauthenticated /api/upload endpoint that accepts arbitrary files with no auth/session/form context
Unauthenticated users can upload arbitrary files to HeyForm, receiving permanent public URLs, bypassing intended access controls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-63429?
CVE-2026-63429 is a high-severity vulnerability in heyform, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-63429?
How do I fix CVE-2026-63429?
No fix has been published for CVE-2026-63429 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-63429 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63429 exists.
Sources
Also known as GHSA-432x-54v2-p7p7.