Read the docs
TI-2026-45208 Aliases CVE-2026-63429

HeyForm has unauthenticated /api/upload endpoint that accepts arbitrary files with no auth/session/form context

Priority HIGH 76CWE-306Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass, Code execution
Confidentiality · integrity · availability
Low · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-306 and CWE-434.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00507 43rd percentileScored 2026-11-07
Fix Fixed heyform (heyform): 3.0.0-rc.9

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
heyformheyformbefore 3.0.0-rc.93.0.0-rc.9Patch availableCNA
  • heyform Vendorheyform Affected before 3.0.0-rc.9 Fixed in 3.0.0-rc.9 Patch available CNA

Remediation

  • Fix · CNA heyform (heyform) Fixed in 3.0.0-rc.9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-63429

References

Other 2

  • TI-2026-27351 HeyForm vulnerable to stored XSS via form field titles CVSS 3.1CRITICAL 9.0
  • TI-2026-56756 HeyForm Reflects Any Origin in CORS Responses While Allowing Credentials CVSS 3.1HIGH 8.1
  • TI-2026-45207 Improper input validation in heyform CVSS 3.1MEDIUM 5.8
  • TI-2026-33532 HeyForm Vulnerable to Stored XSS via Unauthenticated SVG File Upload CVSS 4.0MEDIUM 6.4
  • TI-2026-85482 Stored cross-site scripting in HeyForm via uploaded HTML files CVSS 3.1HIGH 7.6

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences