What is CVE-2026-63429?

CVE-2026-63429 is a high-severity vulnerability in Heyform, classified under Missing Authentication for Critical Function. CVSS score: 8.6/10. Published 2026-07-20.

How severe is CVE-2026-63429?

High severity. CVSS v3 base score is 8.6 out of 10.

Auth bypass in Heyform

CVE-2026-63429

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.

Vulnerability class: Broken Authentication

EPSS: 0.005 (41.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L.

Affected products

Heyform — versions < 3.0.0-rc.9

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-63429?: CVE-2026-63429 is a high-severity vulnerability in Heyform, classified under Missing Authentication for Critical Function. CVSS score: 8.6/10. Published 2026-07-20.
How severe is CVE-2026-63429?: High severity. CVSS v3 base score is 8.6 out of 10.