CVE-2026-63429: high-severity vulnerability in heyform
HeyForm has unauthenticated /api/upload endpoint that accepts arbitrary files with no auth/session/form context
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.6epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
Affected products
heyform · heyformRelated CVEs — heyform
In the same product, most dangerous first.
CVE-2026-45797MEDIUMHeyForm Vulnerable to Stored XSS via Unauthenticated SVG File UploadEPSS 0.6%CVE-2026-82291HIGHHeyForm Reflects Any Origin in CORS Responses While Allowing CredentialsEPSS 0.6%CVE-2026-35198CRITICALHeyForm vulnerable to stored XSS via form field titlesEPSS 0.5%CVE-2026-63428MEDIUMHeyForm: completeSubmission persists submitter-supplied hidden fields verbatim without validating against the form's declared hidden-field setEPSS 0.3%CVE-2026-102615HIGHHeyForm: Uploaded HTML files are served as text/html on the app origin with no CSP — stored XSSEPSS —