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CVE-2026-63429— HeyForm has unauthenticated /api/upload endpoint that accepts arbitrary files with no auth/session/form context

CVSS 8.6 · High EPSS 0.30% · P22

Possible ATT&CK Techniques 1AI

T1136 · Create Account

Affected Version Matrix 1

VendorProductVersion RangeStatus
heyformheyform< 3.0.0-rc.9affected
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I. Basic Information for CVE-2026-63429

Vulnerability Information
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Vulnerability Title
HeyForm has unauthenticated /api/upload endpoint that accepts arbitrary files with no auth/session/form context
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
关键功能的认证机制缺失
Source: CVE Program / CVE List V5
Vulnerability Title
HeyForm 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
HeyForm HeyForm是HeyForm公司的一款表单构建软件。 HeyForm 3.0.0-rc.9之前版本存在安全漏洞，该漏洞源于POST /api/upload端点没有身份验证守卫、全局守卫、表单环境验证、openToken要求和会话cookie检查，任何匿名互联网用户都可以上传文件并获得永久公开URL。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
heyformheyform < 3.0.0-rc.9 -

II. Public POCs for CVE-2026-63429

#POC DescriptionSource LinkShenlong Link
AI-Generated POCPremium
Qwen3.6-35B-A3B · 7453 chars
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III. Intelligence Information for CVE-2026-63429

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Vendor Advisories for CVE-2026-63429 (1)

Same Patch Batch · heyform · 2026-07-20 · 4 CVEs total

CVE-2026-351989.0 CRITICALHeyForm vulnerable to stored XSS via form field titles
CVE-2026-634285.8 MEDIUMHeyForm: completeSubmission persists submitter-supplied hidden fields verbatim without val
CVE-2026-45797HeyForm Vulnerable to Stored XSS via Unauthenticated SVG File Upload

IV. Related Vulnerabilities

Same product: heyform
Same vendor: heyform
Same weakness: CWE-306

V. Comments for CVE-2026-63429

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